US20130252439A1 - Method of Manufacturing Semiconductor Device, Substrate Processing Apparatus and Non-Transitory Computer-Readable Recording Medium - Google Patents

Abstract

A method includes: forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application claims foreign priority under 35 U.S.C. §119(a)-(d) to Application No. JP 2012-064465 filed on Mar. 21, 2012, and to Application No. JP 2013-030452 filed on Feb. 19, 2013, the entire contents of each of which are hereby incorporated by reference.
FIELD OF THE INVENTION
• The present invention relates to a method of manufacturing a semiconductor device including a process of forming a thin film on a substrate, a substrate processing apparatus, and a non-transitory computer-readable recording medium.
BACKGROUND
• In some cases, a process of forming a thin film, such as a silicon oxide (SiO) film or a silicon nitride (SiN) film, on a substrate may be performed as a process included in a process of manufacturing a semiconductor device. The silicon oxide (SiO) film has high insulating properties and low dielectric properties and is thus widely used as an insulating film or an interlayer film. In addition, the silicon nitride (SiN) film has high insulating properties, high corrosion resistance, low dielectric properties, high film stress controllability, etc., and is thus widely used as an insulating film, a mask film, a charge accumulating film, or a stress control film. In addition, a technique of forming a thin film, such as a silicon carbonitride (SiCN) film, a silicon oxycarbonitride (SiOCN) film, a silicon oxycarbide (SiOC) film, or a silicon boron carbonitride (SiBCN) film, by adding carbon (C) and/or boron (B) to the silicon oxide (SiO) film and the silicon nitride (SiN) film has been known. An etching resistance of a thin film may be enhanced by adding carbon (C) thereto.
SUMMARY
• A silicon oxycarbide (SiOC) film may be formed by supplying a source gas containing silicon (Si) (Si-source), a reactive gas containing oxygen (O) (oxygen-containing gas), and a reactive gas containing carbon (C) (carbon-containing gas) to a substrate in a process chamber. A silicon carbonitride (SiCN) film may be formed by supplying a Si source, a reactive gas containing nitrogen (N) (nitrogen-containing gas), and a carbon-containing gas to the substrate in the process chamber.
• In order to increase the concentrations of oxygen, nitrogen, carbon, etc. contained in a thin film, such as the SiOC film or the SiCN film, it is effective to increase the flow rates of reactive gases (an oxygen-containing gas, a nitrogen-containing gas, and a carbon-containing gas) to be supplied into the process chamber. However, if the flow rates of the reactive gases increase, a total supply rate (consumption rate or usage rate) of the reactive gas may increase, thereby increasing film-forming costs. In particular, when expensive gases are used as reactive gases, film-forming costs are very high.
• It is an object of the present invention to provide a method of manufacturing a semiconductor device, which is capable of reducing a total supply rate of reactive gases without lowering the concentrations of, for example, oxygen, nitrogen, and carbon contained in a thin film, a substrate processing apparatus, and a non-transitory computer-readable recording medium.
• According to one aspect of the present invention, there is provided a method of manufacturing a semiconductor device, including: forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the steps (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
• According to another aspect of the present invention, there is provided a substrate processing apparatus including: a process chamber configured to accommodate a substrate; a source gas supply system configured to supply a source gas into the process chamber; a reactive gas supply system configured to supply a reactive gas into the process chamber; an exhaust system configured to exhaust an inside of the process chamber; a pressure regulator configured to regulate pressure in the process chamber; and a control unit configured to control the source gas supply system, the reactive gas supply system, the exhaust system, and the pressure regulator to form a thin film on the substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the steps (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
• According to still another aspect of the present invention, there is provided a non-transitory computer-readable recording medium storing a program that causes a computer to perform a sequence of forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the sequences (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic configuration view of a vertical processing furnace of a substrate processing apparatus according to an exemplary embodiment of the present invention, showing a portion of the processing furnace in a longitudinal cross-sectional view.
• FIG. 2 is a schematic configuration view of the vertical processing furnace of the substrate processing apparatus according to an exemplary embodiment of the present invention, showing the portion of the processing furnace in a cross-sectional view taken along line A-A ofFIG. 1.
• FIG. 3 is a schematic configuration view of a controller of the substrate processing apparatus according to an exemplarily embodiment of the present invention, showing a control system of the controller in a block diagram.
• FIG. 4 is a view showing a film-forming flow according to a first embodiment of the present invention.
• FIG. 5 is a view showing gas supply timing in a film-forming sequence according to the first embodiment of the present invention.
• FIG. 6 is a view showing a film-forming flow according to a second embodiment of the present invention.
• FIG. 7 is a view showing gas supply timing in a film-forming sequence according to the second embodiment of the present invention.
• FIG. 8 is a diagram illustrating the relationship among a flow rate of a reactive gas (TEA), a flow rate of an inert gas (N₂), pressure in a process chamber, a degree of opening of an exhaust valve (APC valve) during a reactive gas (TEA) supply process included in a film-forming sequence according to an embodiment of the present invention.
• FIG. 9 is a view showing gas supply timing in a film-forming sequence according to another embodiment of the present invention.
DETAILED DESCRIPTIONFirst Embodiment of the Present Invention
• A first embodiment of the present invention will now be described with reference to the appended drawings.
(1) Configuration of Substrate Processing Apparatus
• FIG. 1 is a schematic configuration view of avertical processing furnace202 of a substrate processing apparatus according to an exemplary embodiment of the present invention, showing a portion of theprocessing furnace202 in a longitudinal cross-sectional view.FIG. 2 is a schematic configuration view of thevertical processing furnace202 according to an exemplary embodiment of the present invention, showing the portion of theprocessing furnace202 in a cross-sectional view taken along line A-A ofFIG. 1.
• As illustrated inFIG. 1, theprocessing furnace202 includes aheater207 serving as a heating unit (heating mechanism). Theheater207 has a cylindrical shape and is supported by a heater base (not shown) serving as a holding plate to be vertically installed. In addition, theheater207 functions as an activation mechanism (excitation unit) configured to thermally activate (excite) a gas as will be described below.
• Areaction tube203 constituting a reaction container (processing container) to be concentric with theheater207 is installed inside theheater207. Thereaction tube203 is formed of a heat-resistant material, such as quartz (SiO₂), silicon carbide (SiC), or the like, and has a cylindrical shape with an upper end closed and a lower end open. Aprocess chamber201 is formed in a hollow tubular portion of thereaction tube203, and is configured such that wafers200 serving as substrates may be accommodated by a boat217 (to be described below) aligned in a horizontal posture in a multi-stage in a vertical direction.
• Afirst nozzle249a, asecond nozzle249b, and athird nozzle249care installed in theprocess chamber201 to pass through a lower portion of thereaction tube203. A firstgas supply pipe232a, a secondgas supply pipe232band a thirdgas supply pipe232care connected to thefirst nozzle249a, thesecond nozzle249band thethird nozzle249c, respectively. A fourthgas supply pipe232dis connected to the thirdgas supply pipe232c. As described above, the threenozzles249a,249b, and249cand the fourgas supply pipes232a,232b,232c, and232dare installed at thereaction tube203 to supply a plurality of types (here, four types) of gases into theprocess chamber201.
• A manifold formed of metal and configured to support thereaction tube203 may be installed under thereaction tube203, and thenozzles249a,249b, and249cmay be installed to pass through a sidewall of the metal manifold. In this case, an exhaust pipe231 (to be described later) may further be installed at the metal manifold. Alternatively, theexhaust pipe231 may be installed at a lower portion of thereaction tube203 instead of the metal manifold. As described above, a furnace port of theprocessing furnace202 may be formed of a metal, and thenozzles249a,249b, and249cor the like may be installed at the metal furnace port.
• A mass flow controller (MFC)241aserving as a flow rate controller (flow rate control unit) and avalve243aserving as an opening/closing valve are installed at the firstgas supply pipe232ain sequence from an upstream side. In addition, a first inertgas supply pipe232eis connected to the firstgas supply pipe232adownstream from thevalve243a. Amass flow controller241eserving as a flow rate controller (flow rate control unit) and avalve243eserving as an opening/closing valve are installed at the first inertgas supply pipe232ein sequence from the upstream side. Further, the above-mentionedfirst nozzle249ais connected to a tip section of the firstgas supply pipe232a. Thefirst nozzle249ais installed in an arc-shaped space between an inner wall of thereaction tube203 and thewafer200 from a lower portion to an upper portion of the inner wall of thereaction tube203 to stand up in a stacking direction of thewafers200. That is, thefirst nozzle249ais installed in a region horizontally surrounding a wafer arrangement region, in which thewafers200 are arranged, which is a side of the wafer arrangement region, along the wafer arrangement region. Thefirst nozzle249ais constituted by an L-shaped long nozzle, and has a horizontal section installed to pass through a lower sidewall of thereaction tube203 and a vertical section installed to stand up at least from one end side to the other end side of the wafer arrangement region. Agas supply hole250aconfigured to supply a gas is formed in a side surface of thefirst nozzle249a. Thegas supply hole250ais opened toward a center of thereaction tube203 so that a gas may be supplied toward thewafer200. The plurality ofgas supply holes250aare formed from the lower portion to the upper portion of thereaction tube203, have the same opening area, and are formed at the same opening pitch.
• A first gas supply system mainly includes the firstgas supply pipe232a, themass flow controller241a, and thevalve243a. Thefirst nozzle249amay further be included in the first gas supply system. Further, a first inert gas supply system mainly includes the first inertgas supply pipe232e, themass flow controller241e, and thevalve243e. The first inert gas supply system also functions as a purge gas supply system.
• A mass flow controller (MFC)241bserving as a flow rate controller (flow rate control unit) and avalve243bserving as an opening/closing valve are installed at the secondgas supply pipe232bin sequence from the upstream side. In addition, a second inertgas supply pipe232fis connected to the secondgas supply pipe232bdownstream from thevalve243b. Amass flow controller241fserving as a flow rate controller (flow rate control unit) and avalve243fserving as an opening/closing valve are installed at the second inertgas supply pipe232fin sequence from the upstream side. Further, the above-mentionedsecond nozzle249bis connected to a tip section of the secondgas supply pipe232b. Thesecond nozzle249bis installed in an arc-shaped space between the inner wall of thereaction tube203 and thewafer200 from the lower portion to the upper portion of the inner wall of thereaction tube203 to stand up in the stacking direction of thewafers200. That is, thesecond nozzle249bis installed at a region surrounding the wafer arrangement region in which thewafers200 are arranged, which is a side of the wafer arrangement region, along the wafer arrangement region. Thesecond nozzle249bis constituted by an L-shaped long nozzle, and has a horizontal section installed to pass through the lower sidewall of thereaction tube203 and a vertical section installed to stand up at least from the one end side to the other end side of the wafer arrangement region. Agas supply hole250bconfigured to supply a gas is formed in a side surface of thesecond nozzle249b. Thegas supply hole250bis opened toward the center of thereaction tube203 so that a gas may be supplied toward thewafer200. The plurality of gas supply holes250bare installed from the lower portion to the upper portion of thereaction tube203, have the same opening area, and are installed at the same opening pitch.
• A second gas supply system mainly includes the secondgas supply pipe232b, themass flow controller241band thevalve243b. Thesecond nozzle249bmay be further included in the second gas supply system. Further, a second inert gas supply system mainly includes the second inertgas supply pipe232f, themass flow controller241f, and thevalve243f. The second inert gas supply system may function as a purge gas supply system.
• A mass flow controller (MFC)241cserving as a flow rate controller (flow rate control unit) and avalve243cserving as an opening/closing valve are installed at the thirdgas supply pipe232cin sequence from the upstream side. In addition, the fourthgas supply pipe232dis connected to the thirdgas supply pipe232cdownstream from thevalve243c. Amass flow controller241dserving as a flow rate controller (flow rate control unit) and avalve243dserving as an opening/closing valve are installed at the fourthgas supply pipe232din sequence from the upstream side. Further, a third inertgas supply pipe232gis connected to the thirdgas supply pipe232cdownstream from a connecting place to the fourthgas supply pipe232d. Amass flow controller241gserving as a flow rate controller (flow rate control unit) and avalve243gserving as an opening/closing valve are installed at the third inertgas supply pipe232gin sequence from the upstream side. In addition, the above-mentionedthird nozzle249cis connected to a tip section of the thirdgas supply pipe232c. Thethird nozzle249cis installed in an arc-shaped space between the inner wall of thereaction tube203 and thewafer200 from the lower portion to the upper portion of the inner wall of thereaction tube203 to stand up in the stacking direction of thewafers200. That is, thethird nozzle249cis installed at the region horizontally surrounding the wafer arrangement region in which thewafers200 are arranged, which is a side of the wafer arrangement region, along the wafer arrangement region. Thethird nozzle249cis constituted by an L-shaped long nozzle, and has a horizontal section installed to pass through the lower sidewall of thereaction tube203 and a vertical section installed to stand up at least from the one end side to the other end side of the wafer arrangement region. Agas supply hole250cconfigured to supply a gas is formed in a side surface of thethird nozzle249c. Thegas supply hole250cis opened toward the center of thereaction tube203 so that a gas may be supplied toward thewafer200. The plurality of gas supply holes250care formed from the lower portion to the upper portion of thereaction tube203, have the same opening area, and are installed at the same opening pitch.
• A third gas supply system mainly includes the thirdgas supply pipe232c, themass flow controller241c, and thevalve243c. Thethird nozzle249cmay be further included in the third gas supply system. Further, a fourth gas supply system mainly includes the fourthgas supply pipe232d, themass flow controller241d, and thevalve243d. In addition, thethird nozzle249cdisposed at a downstream side of a connecting section of the thirdgas supply pipe232cwith the fourthgas supply pipe232dmay be included in the fourth gas supply system. In addition, a third inert gas supply system mainly includes the third inertgas supply pipe232g, themass flow controller241g, and thevalve243g. The third inert gas supply system also functions as a purge gas supply system.
• As described above, in the method of supplying a gas according to the first embodiment, the gas is conveyed via thenozzles249a,249b, and249cdisposed in an arc-shaped longitudinal long space defined by the inner wall of thereaction tube203 and the end section of the plurality of stackedwafers200, the gas is firstly ejected into thereaction tube203 near thewafer200 through the gas supply holes250a,250b, and250copened at thenozzles249a,249band249c, respectively, and thus a main stream of the gas in thereaction tube203 is in a direction parallel to the surface of thewafer200, i.e., in a horizontal direction. According to the above-mentioned configuration, the gas may be evenly supplied to thewafer200, and a film thickness of a thin film formed on thewafer200 may be uniformized. In addition, while the gas flowing on the surface of thewafer200, i.e., the gas remaining after reaction, flows in a direction of an exhaust port, i.e., the exhaust pipe231 (to be described later), the direction in which the remaining gas flows is appropriately specified at a position of the exhaust port and not limited to the vertical direction.
• A chlorosilane-based source gas that is a source gas containing a specific element and a halogen element, for example, a source gas containing at least silicon (Si) and chlorine (Cl), is supplied into theprocess chamber201 via themass flow controller241a, thevalve243a, and thefirst nozzle249athrough the firstgas supply pipe232a. Here, the chlorosilane-based source gas means a chlorosilane-based source material in a gaseous state, for example, a gas obtained by evaporating a chlorosilane-based source material in a liquid state under a normal temperature and a normal pressure, or a chlorosilane-based source material in a gaseous state under a normal temperature and a normal pressure. In addition, the chlorosilane-based source material means a silane-based source material including a chloro group which is a halogen group, and a source material including at least silicon (Si) and chlorine (Cl). That is, here, the chlorosilane-based source material may refer to a type of halide. In addition, the term “source material” used in the present disclosure may refer to “a liquid source material in a liquid state,” “a source gas in a gaseous state,” or both of these. Accordingly, the term “chlorosilane-based source material” used in the present disclosure may refer to “a chlorosilane-based source material in a liquid state,” “a chlorosilane-based source gas in a gaseous state,” or both of these. For example, hexachlorodisilane (Si₂Cl₆, abbreviated to ‘HCDS’) gas may be used as the chlorosilane-based source gas. In addition, when the liquid source material in the liquid state is used under the normal temperature and normal pressure as the HCDS gas, the liquid source material is evaporated by an evaporation system, such as an evaporator, a bubbler, or the like, to be supplied as a source gas (HCDS gas).
• For example, a gas containing an amine, i.e., an amine-based gas, which is a reactive gas (first reactive gas) containing carbon (C) and nitrogen (N), is supplied into theprocess chamber201 via themass flow controller241b, thevalve243b, and thesecond nozzle249bthrough the secondgas supply pipe232b. Here, the amine-based gas is an amine in a gaseous state, for example, a gas obtained by evaporating an amine in a liquid state under the normal temperature and normal pressure, or a gas containing an amine group such as amine in a gaseous state under the normal temperature and normal pressure. The amine-based gas includes an amine, such as ethylamine, methylamine, propylamine, isopropylamine, butylamine, isobutylamine, or the like. Here, “amine” is a general name of a compound in which a hydrogen atom of ammonia (NH₃) is substituted with a hydrocarbon group such as an alkyl group or the like. That is, the amine includes a hydrocarbon group such as an alkyl group or the like, which is a ligand including a carbon atom. The amine-based gas may refer to a gas containing no silicon because the gas includes three elements of carbon (C), nitrogen (N), and hydrogen (H) but does not include silicon (Si), and may refer to a gas containing no silicon and no metal because the gas does not include silicon or a metal. In addition, the amine-based gas may be a nitrogen-containing gas, a carbon-containing gas, or a hydrogen-containing gas. The amine-based gas may be a gas containing only three elements of carbon (C), nitrogen (N), and hydrogen (H) constituting the amine group. In addition, the term “amine” used in the present disclosure may mean “an amine in a liquid state,” “an amine-based gas in a gaseous state,” or both of these. For example, triethylamine [(C₂H₅)₃N, abbreviated to TEA] gas may be used as the amine-based gas. In addition, when an amine such as TEA that is in a liquid state under a normal temperature and normal pressure is used, the amine in the liquid state is evaporated by an evaporation system, such as an evaporator, a bubbler, or the like, to be supplied as a first reactive gas (TEA gas).
• For example, a gas including oxygen (O) (oxygen-containing gas), i.e., an oxidizing gas (oxidant gas), which is a reactive gas that is different from the first reactive gas (second reactive gas), is supplied into theprocess chamber201 via themass flow controller241c, thevalve243c, and thethird nozzle249cthrough the thirdgas supply pipe232c. For example, oxygen (O₂) gas may be used as the oxygen-containing gas.
• For example, a gas including nitrogen (N) (nitrogen-containing gas), i.e., a nitriding gas (nitridant gas), which is a reactive gas that is different from the first reactive gas (second reactive gas), is supplied into theprocess chamber201 via themass flow controller241d, thevalve243d, the thirdgas supply pipe232c, and thethird nozzle249cthrough the fourthgas supply pipe232d. For example, ammonia (NH₃) gas may be used as the nitrogen-containing gas.
• For example, nitrogen (N₂) gas, which is an inert gas, is supplied into theprocess chamber201 via themass flow controllers241e,241f, and241g, thevalves243e,243f, and243g, thegas supply pipes232a,232b, and232c, and thenozzles249a,249b, and249cthrough the inertgas supply pipes232e,232f, and232g.
• In addition, for example, when the above-mentioned gases flow through the respective gas supply pipes, a source gas supply system configured to supply a source gas including a specific element and a halogen group, i.e., a chlorosilane-based source gas supply system, is constituted by the first gas supply system. Further, the chlorosilane-based source gas supply system is also referred to simply as a chlorosilane-based source material supply system. Furthermore, a reactive gas supply system (first reactive gas supply system), i.e., an amine-based gas supply system, is constituted by the second gas supply system. In addition, the amine-based gas supply system is also referred to simply as an amine supply system. Further, a reactive gas supply system (second reactive gas supply system), i.e., an oxygen-containing gas supply system serving as an oxidizing gas supply system, is constituted by the third gas supply system. Furthermore, a reactive gas supply system (second reactive gas supply system), i.e., a nitrogen-containing gas supply system serving as a nitriding gas supply system, is constituted by the fourth gas supply system.
• Theexhaust pipe231 configured to exhaust an atmosphere in theprocess chamber201 is installed in thereaction tube203. When seen in a transverse cross-sectional view as shown inFIG. 2, theexhaust pipe231 is installed at a side of thereaction tube203 opposite to a side in which thegas supply hole250aof thefirst nozzle249a, thegas supply hole250bof thesecond nozzle249b, and thegas supply hole250cof thethird nozzle249care formed, i.e., an opposite side of the gas supply holes250a,250b, and250cvia thewafer200. In addition, when seen in a longitudinal cross-sectional view as shown inFIG. 1, theexhaust pipe231 is installed under a place in which the gas supply holes250a,250b, and250care formed. According to the configuration, the gas supplied in the vicinity of thewafer200 in theprocess chamber201 through the gas supply holes250a,250b, and250cflows in a horizontal direction, i.e., in a direction parallel to the surface of thewafer200, then flows downward, and then is exhausted through theexhaust pipe231. A main flow of the gas in theprocess chamber201 becomes a flow in the horizontal direction as described above.
• Avacuum pump246 serving as a vacuum exhaust apparatus is connected to theexhaust pipe231 via apressure sensor245 serving as a pressure detector (pressure detection unit) configured to detect the pressure in theprocess chamber201 and an APC (Auto Pressure Controller)valve244 serving as a pressure regulator (pressure regulation unit) which is an exhaust valve. In addition, theAPC valve244 is a valve configured to perform the vacuum exhaust of the inside of theprocess chamber201 and stop the vacuum exhaust by opening/closing the valve in a state in which thevacuum pump246 is operated, and configured to regulate the pressure in theprocess chamber201 by adjusting a valve opening angle in a state in which thevacuum pump246 is operated. An exhaust system, i.e., an exhaust line, mainly includes theexhaust pipe231, theAPC valve244, and thepressure sensor245. Thevacuum pump246 may further be included in the exhaust system (exhaust line). The exhaust system (exhaust line) is configured to perform the vacuum exhaust such that the pressure in theprocess chamber201 arrives at a predetermined pressure (vacuum level) by adjusting the valve opening angle of theAPC valve244 based on the pressure information detected by thepressure sensor245 while operating thevacuum pump246.
• Aseal cap219 serving as a furnace port cover configured to hermetically seal the lower end opening of thereaction tube203 is installed under thereaction tube203. Theseal cap219 is configured to abut the lower end of thereaction tube203 from a lower side in the vertical direction. Theseal cap219 is formed of a metal such as stainless steel or the like, and has a disc shape. An O-ring220 serving as a seal member configured to abut the lower end of thereaction tube203 is installed at an upper surface of theseal cap219. Arotary mechanism267 configured to rotate theboat217 serving as a substrate holder (to be described later) is installed at a side of theseal cap219 opposite to theprocess chamber201. Arotary shaft255 of therotary mechanism267 is connected to theboat217 through theseal cap219. Therotary mechanism267 is configured to rotate theboat217 to rotate thewafer200. Theseal cap219 is constituted to be raised and lowered in the vertical direction by aboat elevator115 serving as a raising/lowering mechanism vertically installed at the outside of thereaction tube203. Theboat elevator115 is configured to load and unload theboat217 into and from theprocess chamber201 by raising and lowering theseal cap219. That is, theboat elevator115 is constituted by a conveyance apparatus (conveyance mechanism) configured to convey theboat217, i.e., thewafer200, to/from theprocess chamber201.
• Theboat217 serving as a substrate support member is formed of a heat resistant material, such as quartz, silicon carbide, or the like, and configured to concentrically align the plurality ofwafers200 in a horizontal posture and support thewafers200 in a multi-stage. In addition, an insulatingmember218 formed of a heat resistant material, such as quartz, silicon carbide, or the like, is installed under theboat217 so that heat from theheater207 cannot be easily transferred toward theseal cap219. Further, the insulatingmember218 may be constituted by a plurality of insulating plates formed of a heat resistant material, such as quartz, silicon carbide, or the like, and an insulating plate holder configured to support the insulating plate in a horizontal posture in a multi-stage.
• Atemperature sensor263 serving as a temperature detector is installed in thereaction tube203, and an electrical connection state to theheater207 is adjusted based on the temperature information detected by thetemperature sensor263 so that the temperature in theprocess chamber201 may have a desired temperature distribution. Thetemperature sensor263 has an L shape similar to thenozzles249a,249b, and249c, and is installed along the inner wall of thereaction tube203.
• As shown inFIG. 3, acontroller121 serving as a control unit (control unit) is constituted by a computer including a central processing unit (CPU)121a, a random access memory (RAM)121b, amemory device121c, and an input/output (I/O)port121d. TheRAM121b, thememory device121cand the I/O port121dare configured to exchange data with theCPU121avia aninternal bus121e. An input/output (I/O)device122 constituted by, for example, a touch panel or the like, is connected to thecontroller121.
• Thememory device121cis constituted by, for example, a flash memory, a hard disk drive (HDD), or the like. A control program configured to control an operation of a substrate processing apparatus or a process recipe in which a sequence or conditions of substrate processing (to be described later) is readably stored in thememory device121c. In addition, the process recipe is provided by assembling sequences in a substrate processing process (to be described below) to be performed in thecontroller121 to obtain a predetermined result, and functions as a program. Hereinafter, the process recipe or the control program is generally and simply referred to as a program. In addition, the term “program” used in the present disclosure may include only the process recipe, only the control program, or both of these. Further, theRAM121bis constituted by a memory region (work area) in which a program or data read by theCPU121ais temporarily stored.
• The I/O port121dis connected to the above-mentionedmass flow controllers241a,241b,241c,241d,241e,241f, and241g, thevalves243a,243b,243c,243d,243e,243f, and243g, thepressure sensor245, theAPC valve244, thevacuum pump246, theheater207, thetemperature sensor263, therotary mechanism267, theboat elevator115, etc.
• TheCPU121ais configured to read and execute the control program from thememory device121c, and to read the process recipe from thememory device121c, according to an operation command input via the input/output device122. In addition, theCPU121ais configured to control a flow rate control operation of various gases by themass flow controllers241a,241b,241c,241d,241e,241f, and241g, an opening/closing operation of thevalves243a,243b,243c,243d,243e,243f, and243g, an opening/closing operation of theAPC valve244, a pressure regulation operation by theAPC valve244 based on thepressure sensor245, a temperature control operation of theheater207 based on thetemperature sensor263, start and stoppage of thevacuum pump246, a rotation and rotational speed control operation of theboat217 by therotary mechanism267, a raising/lowering operation of theboat217 by theboat elevator115, etc., according to contents of the read process recipe.
• In addition, thecontroller121 is not limited to being constituted by an exclusive computer, and may be constituted by a general computer. For example, thecontroller121 according to the first embodiment may be constituted by preparing anexternal memory device123 in which the above-mentioned program is stored (for example, a magnetic tape, a magnetic disk such as a flexible disk, a hard disk, or the like, an optical disc such as a CD, a DVD, or the like, an optical magnetic disc such as MO, or a semiconductor memory such as a USB memory, a memory card, or the like), and installing the program in the general computer using the above-mentionedexternal memory device123. Further, a unit configured to supply a program to the computer is not limited to the case in which the program is supplied via theexternal memory device123. For example, the program may be supplied using a communication unit, such as the Internet or an exclusive line, without theexternal memory device123. In addition, thememory device121cor theexternal memory device123 is constituted by a non-transitory computer-readable recording medium. Hereinafter, these are generally and simply referred to as non-transitory computer-readable recording media. Further, the term “non-transitory computer-readable recording medium” used in the present disclosure may include only thememory device121c, only theexternal memory device123, or both of these.
(2) Substrate Processing Process
• Next, a method of forming a thin film on thewafer200 using theprocessing furnace202 of the substrate processing apparatus as described above will be described. In the following description, operations of the respective parts constituting the substrate processing apparatus are controlled by thecontroller121.
• According to the first embodiment, a thin film is formed on thewafer200 in theprocess chamber201 by performing a cycle a predetermined number of times (once or more), the cycle including a process of supplying a source gas to thewafer200 and a process of supplying a reactive gas to thewafer200.
• During at least one process among the process of supplying the source gas and the process of supplying the reactive gas, a first supply process of supplying the source gas or the reactive gas used in the at least one process at a first flow rate is performed while exhausting of an atmosphere in theprocess chamber201 is suspended until pressure in theprocess chamber201 reaches a predetermined pressure; and a second supply process of supplying the source gas or the reactive gas used in the at least one process at a second flow rate, which is less than the first flow rate, is performed in a state in which the atmosphere in theprocess chamber201 is exhausted while maintaining the predetermined pressure in theprocess chamber201, after the pressure in theprocess chamber201 reaches the predetermined pressure.
• Further, in the first embodiment, conditions of supplying a plurality of types of gases including a plurality of elements forming the thin film are controlled such that a composition ratio of the thin film has a stoichiometric composition or a predetermined composition ratio different from the stoichiometric composition. For example, the supply conditions are controlled such that at least one element among the plurality of elements forming the thin film is more excessive than the other elements, with respect to the stoichiometric composition. Hereinafter, an example in which the film-forming is performed while controlling a ratio of the plurality of elements forming the thin film, i.e., a composition ratio of the thin film, will be described.
• A film-forming sequence according to the first embodiment will now be described with reference toFIGS. 4 and 5 in detail.FIG. 4 is a view showing a film-forming flow according to the first embodiment.FIG. 5 is a view showing gas supply timing in the film-forming sequence according to the first embodiment.
• In addition, here, an example of a process of forming a silicon oxycarbonitride (SiOCN) film or a silicon oxycarbide (SiOC) film, which is a silicon-based insulating film having a predetermined composition and a predetermined thickness on thewafer200 by performing a cycle a predetermined number of times (n times), the cycle including: a process of forming a silicon-containing layer containing chlorine on thewafer200 in theprocess chamber201 by supplying HCDS gas (which is a chlorosilane-based source gas) as a source gas to thewafer200 in theprocess chamber201, a process of forming a first layer containing silicon, nitrogen, and carbon on thewafer200 by modifying the silicon-containing layer containing chlorine by supplying TEA gas (which is an amine-based gas) as a first reactive gas, and a process of forming a SiOCN film or a SiOC film as a second layer by modifying the first layer by supplying O₂gas (oxygen-containing gas) as a second reactive gas (which is different from the source gas and the first reactive gas) on thewafer200 in theprocess chamber201, will be described.
• In addition, here, in a process of supplying the TEA gas among three processes, i.e., the process of supplying the HCDS gas, the process of supplying TEA gas, and a process of supplying O₂gas, a first supply process of supplying the TEA gas at a first flow rate in a state in which exhausting an atmosphere in theprocess chamber201 is suspended until the pressure in theprocess chamber201 reaches a predetermined pressure (hereinafter referred to as ‘first TEA gas supply process’); and a second supply process of supplying the TEA gas at a second flow rate which is less than the first flow rate in a state in which the atmosphere in theprocess chamber201 is exhausted while maintaining the predetermined pressure in theprocess chamber201, after the pressure in theprocess chamber201 reaches the predetermined pressure (hereinafter referred to as ‘second TEA gas supply process’) will be described.
• The term “wafer” used in the present disclosure may mean only “the wafer itself,” or “a stacked structure (assembly) of the wafer and a layer or film formed on a surface thereof, i.e., the wafer including the layer or film formed on the surface thereof.” In addition, the term “a surface of a wafer” used in the present disclosure may mean “an (exposed) surface of the wafer itself,” or “a surface of the layer or film formed on the wafer, i.e., an outermost surface of the wafer, which is a stacked structure.
• Accordingly, an expression “predetermined gas is supplied to a wafer” in the present disclosure may mean “predetermined gas is directly supplied to an (exposed) surface of the wafer itself,” or “predetermined gas is supplied to a layer or film formed on the wafer, i.e., the outermost surface of the wafer, which is a stacked structure.” In addition, an expression “predetermined layer (or film) is formed on a wafer” in the present disclosure may mean “predetermined layer (or film) is directly formed on an (exposed) surface of the wafer itself,” or “predetermined layer (or film) is formed on a layer or film formed on the wafer, i.e., the outermost surface of the wafer, which is a stacked structure.”
• In addition, the term “substrate” used in the present disclosure is similar to the term “wafer,” and thus “wafer” and “substrate” may be used synonymously in the present disclosure.
• Wafer Charging and Boat Loading
• When a plurality ofwafers200 are loaded in the boat217 (wafer charging), theboat217 supporting the plurality ofwafers200 is raised by theboat elevator115 to be loaded into the process chamber201 (boat loading), as illustrated inFIG. 1. In this state, theseal cap219 seals the lower end of thereaction tube203 via the O-ring220.
• Pressure Regulation and Temperature Control
• The inside of theprocess chamber201 is vacuum-exhausted to a predetermined pressure (vacuum level) by thevacuum pump246. In this case, the pressure in theprocess chamber201 is measured by thepressure sensor245, and theAPC valve244 is feedback-controlled based on the measured pressure information (pressure regulation). In addition, thevacuum pump246 maintains an always-operating state at least until the processing of thewafer200 is terminated. Further, the inside of theprocess chamber201 is heated to a desired temperature by theheater207. In this case, an electrical connection state to theheater207 is feedback-controlled based on the temperature information detected by thetemperature sensor263 such that the inside of theprocess chamber201 has a desired temperature distribution (temperature control). In addition, the heating of the inside of theprocess chamber201 by theheater207 is continuously performed at least until the processing of thewafer200 is terminated. Next, rotation of theboat217 and thewafer200 is started by therotary mechanism267. The rotation of theboat217 and thewafer200 by therotary mechanism267 is continuously performed at least until the processing of thewafer200 is terminated.
• Process of Forming Silicon Oxycarbonitride Film or Silicon Oxycarbide Film
• Next, the following three steps, i.e., steps 1 to 3, are sequentially performed.
Step 1
• HCDS Gas Supply
• Thevalve243aof the firstgas supply pipe232ais opened to cause HCDS gas to flow through the firstgas supply pipe232a. The flow rate of the HCDS gas flowing through the firstgas supply pipe232ais controlled by themass flow controller241a. The flow-rate-controlled HCDS gas is supplied into theprocess chamber201 through thegas supply hole250aof thefirst nozzle249ato be exhausted through theexhaust pipe231. Here, the HCDS gas is supplied to thewafer200. Here, simultaneously, thevalve243eis opened to cause N₂gas, which is an inert gas, to flow through the first inertgas supply pipe232e. The flow rate of the N₂gas flowing through the first inertgas supply pipe232eis controlled by themass flow controller241e. The flow-rate-controlled N₂gas is supplied into theprocess chamber201 to be exhausted through theexhaust pipe231 with the HCDS gas.
• In addition, here, in order to prevent invasion of HCDS gas into thesecond nozzle249band thethird nozzle249c, thevalves243f, and243gare opened to cause the N₂gas to flow through the second inertgas supply pipe232fand the third inertgas supply pipe232g. The N₂gas is supplied into theprocess chamber201 to be exhausted through theexhaust pipe231 via the secondgas supply pipe232b, the thirdgas supply pipe232c, thesecond nozzle249b, and thethird nozzle249c.
• Here, theAPC valve244 is appropriately adjusted such that the pressure in theprocess chamber201 is within a range of, for example, 1 to 13,300 Pa, and preferably 20 to 1,330 Pa. A supply flow rate of the HCDS gas controlled by themass flow controller241ais a flow rate within a range of, for example, 1 to 1,000 sccm. Each supply flow rate of the N₂gas controlled by themass flow controllers241e,241f, and241gis a flow rate within a range of, for example, 100 to 10,000 sccm. A time in which the HCDS gas is supplied to thewafer200, i.e., a gas supply time (exposure time), is a time within a range of, for example, 1 to 120 seconds, and preferably 1 to 60 seconds. Here, a temperature of theheater207 is set such that the temperature of thewafer200 is a temperature within a range of, for example, 250 to 700° C., preferably 300 to 650° C., and more preferably 350 to 600° C. In addition, when the temperature of thewafer200 is less than 250° C., a practical film-forming speed may not be accomplished because the HCDS cannot be easily chemisorbed onto thewafer200. This problem may be solved by increasing the temperature of the wafer to 200 to 250° C. or more. Further, when the temperature of thewafer200 is set to 300° C. or more, or 350° C. or more, the HCDS may be more sufficiently absorbed onto thewafer200, and a more sufficient film-forming speed can be accomplished. In addition, when the temperature of thewafer200 exceeds 700° C., the CVD reaction is strengthened (a gas phase reaction becomes dominant), and thus film thickness uniformity is likely to be degraded, making it difficult to control the film thickness uniformity. When the temperature of thewafer200 is set to 700° C. or less, degradation of the film thickness uniformity can be suppressed to enable the control thereof. In particular, when the temperature of thewafer200 is 650° C. or less, or 600° C. or less, the surface reaction becomes dominant, and the film thickness uniformity can be easily accomplished to enable easy control thereof. Accordingly, the temperature of thewafer200 may be a temperature within a range of 250 to 700° C., preferably 300 to 650° C., and more preferably 350 to 600° C.
• A silicon-containing layer including chlorine (Cl) and having a thickness of, for example, less than one atomic layer to several atomic layers is formed on the wafer200 (a base film on a surface of the wafer200) as a seed layer including a specific element (silicon) and a halogen element (chlorine) by supplying the HCDS gas to thewafer200 under the above-mentioned conditions. A silicon-containing layer including Cl may include an adsorption layer of the HCDS gas, a silicon (Si) layer including Cl, or both of these.
• Here, the silicon layer including Cl is a general name including a continuous layer composed of silicon (Si) and including Cl, a discontinuous layer, and a silicon thin film formed by overlapping them and including Cl. In addition, the continuous layer composed of Si and including Cl may refer to a silicon thin film including Cl. Further, Si forming the silicon layer including Cl may include Cl bonds that are completely broken, in addition to Cl bonds that are not completely broken.
• The adsorption layer of the HCDS gas also includes a discontinuous chemical adsorption layer in addition to the continuous chemical adsorption layer of gas molecules of HCDS gas. That is, the adsorption layer of the HCDS gas includes a chemical adsorption layer composed of HCDS molecules and having a thickness of one molecular layer or less than one molecular layer. In addition, HCDS (Si₂Cl₆) molecules forming the adsorption layer of the HCDS gas may also include the Si and Cl bonds that are partially broken, i.e., Si_xCl_ymolecules. That is, the adsorption layer of the HCDS gas includes a continuous chemical adsorption layer or a discontinuous chemical adsorption layer of Si₂Cl₆molecules and/or Si_xCl_ymolecules.
• In addition, the layer having a thickness of less than one atomic layer is an atomic layer that is discontinuously formed, and the layer having a thickness of one atomic layer is an atomic layer that is continuously formed. Further, the layer having a thickness of less than one molecular layer is a molecular layer that is discontinuously formed, and the layer having a thickness of one molecular layer is a molecular layer that is continuously formed.
• Si is deposited on thewafer200 to form the silicon layer including Cl under the conditions in which the HCDS gas is autolyzed (pyrolyzed), i.e., the conditions in which a pyrolysis reaction of the HCDS is generated. The HCDS gas is adsorbed onto thewafer200 to form the adsorption layer of the HCDS gas under the conditions in which the HCDS gas is not autolyzed (pyrolyzed), i.e., the conditions in which a pyrolysis reaction of the HCDS is not generated. In addition, a film-forming rate may be higher when the silicon layer including Cl is formed on thewafer200 than when the adsorption layer of the HCDS gas is formed on thewafer200.
• When the thickness of the silicon-containing layer including Cl formed on thewafer200 exceeds several atomic layers, an effect of modification in the followingstep 2 andstep 3 is not delivered to the entire silicon-containing layer including Cl. In addition, a minimum value of the thickness of the silicon-containing layer including Cl to be formed on thewafer200 is less than one atomic layer. Accordingly, the thickness of the silicon-containing layer including Cl may be less than one atomic layer to about several atomic layers. Further, when the thickness of the silicon-containing layer including Cl is one atomic layer or less, i.e., one atomic layer or less than one atomic layer, the effect of the modification reaction in the followingstep 2 andstep 3 can be relatively improved, and a time needed for the modification reaction insteps 2 and 3 can be reduced. A time needed to form the silicon-containing layer including Cl instep 1 can also be reduced. Eventually, a processing time per cycle can be reduced, thereby reducing a total processing time. That is, the film-forming rate can also be increased. In addition, when the thickness of the silicon-containing layer including Cl is one atomic layer or less, controllability of the film thickness uniformity can also be increased.
• Remaining Gas Removal
• After the silicon-containing layer including Cl is formed as a seed layer, thevalve243aof the firstgas supply pipe232ais closed to stop supply of the HCDS gas. Here, the inside of theprocess chamber201 is vacuum-exhausted by thevacuum pump246 in a state in which theAPC valve244 of theexhaust pipe231 is open (preferably, in a state in which theAPC valve244 is fully open), and the HCDS gas after non-reaction or contribution to formation of the seed layer and remaining in theprocess chamber201 is removed from the inside of theprocess chamber201. In this case, supply of the N₂gas, which is an inert gas, into theprocess chamber201 is maintained in a state in which thevalves243e,243f, and243gare open. The N₂gas serves as a purge gas, and thus an effect of removing the HCDS gas after non-reaction or contribution to formation of the seed layer and remaining in theprocess chamber201 from the inside of theprocess chamber201 can be increased.
• In addition, here, the gas remaining in theprocess chamber201 may not be completely removed, and the inside of theprocess chamber201 may not be completely purged. When the gas remaining in theprocess chamber201 is minute, there is no bad influence onstep 2 performed thereafter. Here, a flow rate of the N₂gas supplied into theprocess chamber201 need not be a large flow rate, and for example, an amount of N₂gas substantially equal to a capacity of the reaction tube203 (the process chamber201) may be supplied to perform the purge such that no bad influence is generated instep 2. As described above, as the inside of theprocess chamber201 is not completely purged, the purge time can be reduced to improve throughput. In addition, consumption of the N₂gas can be suppressed to a necessary minimum value.
• In addition to hexachlorodisilane (Si₂Cl₆, abbreviated to HCDS) gas, an inorganic source gas such as tetrachlorosilane, i.e., silicontetrachloride (SiCl₄, abbreviated to STC) gas, trichlorosilane (SiHCl₃, abbreviated to TCS) gas, dichlorosilane (SiH₂Cl₂, abbreviated to DCS) gas, monochlorosilane (SiH₃Cl, abbreviated to MCS) gas, or the like, may be used as the chlorosilane-based source gas. In addition to the N₂gas, a rare gas such as Ar gas, He gas, Ne gas, Xe gas, or the like may be used as the inert gas.
Step 2
• TEA Gas Supply
• Afterstep 1 is terminated and the remaining gas in theprocess chamber201 is removed, thevalve243bof the secondgas supply pipe232bis opened to cause the TEA gas to flow through the secondgas supply pipe232b. The flow rate of the TEA gas flowing through the secondgas supply pipe232bis controlled by themass flow controller241b. The flow-rate-controlled TEA gas is supplied into theprocess chamber201 through thegas supply hole250bof thesecond nozzle249b. The TEA gas supplied into theprocess chamber201 is thermally activated (excited) to be exhausted through theexhaust pipe231. Here, the thermally activated TEA gas is supplied to thewafer200. Simultaneously, thevalve243fis opened to cause the N₂gas, which is an inert gas, to flow through the second inertgas supply pipe232f. The flow rate of the N₂gas flowing through the second inertgas supply pipe232fis controlled by themass flow controller241f. The flow-rate-controlled N₂gas is supplied into theprocess chamber201 to be exhausted through theexhaust pipe231, together with the TEA gas.
• In addition, here, in order to prevent invasion of the TEA gas into thefirst nozzle249aand thethird nozzle249c, thevalves243eand243gare opened to cause the N₂gas to flow through the first inertgas supply pipe232eand the third inertgas supply pipe232g. The N₂gas is supplied into theprocess chamber201 via the firstgas supply pipe232a, the thirdgas supply pipe232c, thefirst nozzle249aand thethird nozzle249c, and is exhausted through theexhaust pipe231.
• The TEA gas can be supplied to thewafer200 to react the silicon-containing layer including Cl, which is a seed layer formed on thewafer200 instep 1, under the above-mentioned conditions. That is, atoms (Cl atoms) of a halogen element included in the silicon-containing layer including Cl, which is a seed layer, can be reacted with ligands (ethyl groups) included in the TEA gas. Accordingly, as at least some Cl included in the seed layer is drawn (separated) from the seed layer, and simultaneously, at least some ethyl groups of the plurality of ethyl groups included in the TEA gas can be separated from the TEA gas. Then, N of the TEA gas from which at least some ethyl groups are separated can be bonded to Si included in the seed layer. That is, N forming the TEA gas, from which at least some ethyl groups are separated, and including dangling bonds, can be bonded to Si included in the seed layer including dangling bonds, or Si that includes the dangling bonds, forming Si—N bonds. In addition, here, C included in the ethyl group (—CH₂CH₃) separated from the TEA gas can be bonded to Si included in the seed layer, thereby forming Si—C bonds. As a result, Cl is desorbed from the seed layer, and a N component is newly introduced into the seed layer. In addition, here, a C component is also newly introduced into the seed layer.
• Since the TEA gas can be supplied to appropriately react the silicon-containing layer including Cl, which is a seed layer, with the TEA gas under the above-mentioned conditions, the series of reactions described above can be generated.
• The N component and the C component are newly introduced into the seed layer while Cl is desorbed from the seed layer by the series of reactions, and the silicon-containing layer including Cl, which is a seed layer, is changed (modified) into the first layer including silicon (Si), nitrogen (N) and carbon (C), i.e., the silicon carbonitride (SiCN) layer. The first layer becomes a layer including Si, N and C and having a thickness of less than one atomic layer to several atomic layers. In addition, the first layer becomes a layer having a relatively high ratio of a Si component and a C component, i.e., a Si-rich or C-rich layer.
• In addition, when a layer including Si, N, and C is formed as the first layer, chlorine (Cl) included in the silicon-containing layer including Cl and hydrogen (H) included in the TEA gas composes a gaseous material, such as chlorine (Cl₂) gas, hydrogen (H₂) gas, or hydrogen chloride (HCl) gas, and is discharged from the inside of theprocess chamber201 via theexhaust pipe231 during a modification reaction of the silicon-containing layer including Cl by the TEA gas. That is, impurities, such as Cl or the like, in the seed layer are drawn or desorbed from the seed layer to be separated from the seed layer. Accordingly, the first layer becomes a layer having a smaller amount of impurities such as Cl or the like than the seed layer.
• In addition, instep 2, the flow rate of the TEA gas, the flow rate of the N₂gas, and the pressure in theprocess chamber201 are controlled by themass flow controller241b, themass flow controller241f, and theAPC valve244 as illustrated inFIG. 8.FIG. 8 illustrates the relationship among the flow rate of the reactive gas (TEA gas), the flow rate of the inert gas (N₂gas), the pressure in theprocess chamber201, and the degree of opening of the exhaust valve (APC valve) instep 2, i.e., the process of the reactive gas (TEA gas).
• When the TEA gas is supplied instep 2, first, the TEA gas is supplied at the first flow rate (first TEA gas supply process). Then, after the pressure in theprocess chamber201 reaches a predetermined pressure, the TEA gas is supplied at the second flow rate that is less than the first flow rate while maintaining the pressure in the process chamber201 (second TEA gas supply process). In other words, instep 2, during the supply of the TEA gas, the TEA gas is initially supplied at a comparatively high flow rate, and the flow rate of the TEA gas is lowered after a predetermined time and in a stable state in which the pressure in theprocess chamber201 reaches a predetermined pressure, while maintaining the predetermined pressure in theprocess chamber201. In this case, instep 2, a total supply rate of the TEA gas into theprocess chamber201, i.e., a consumption rate of the TEA gas, may be lowered more than when the TEA gas is supplied at the first flow rate into theprocess chamber201.
• In addition, the degree of opening of theAPC valve244 installed at an exhaust line configured to exhaust the inside of theprocess chamber201 may be set to a first degree of opening when the TEA gas is supplied at the first flow rate, and may be set to be a second degree of opening (which is greater (wider) than the first degree of opening) when the TEA gas is supplied at the second flow rate. That is, an exhaust conductance at an exhaust line configured to exhaust the inside of theprocess chamber201 may be set to be a first exhaust conductance, and when the TEA gas is supplied at the second flow rate, may be set to be a second exhaust conductance that is greater than the first exhaust conductance when the TEA gas is supplied at the first flow rate. In other words, when the TEA gas is supplied at the first flow rate, the degree of opening of theAPC valve244 may be set to be the first degree of opening that is less (narrower) than the second degree of opening and the exhaust conductance may be set to be the first exhaust conductance that is less than the second exhaust conductance. In this case, when the TEA gas is supplied at the first flow rate, a total flow rate of gases supplied into the process chamber201 (i.e., the sum of the flow rate of the TEA gas and the flow rate of the N₂gas) may be greater than an exhaust flow rate of a gas exhausted via the exhaust line. In this case, the pressure in theprocess chamber201 may be rapidly raised and may thus be regulated to a predetermined pressure within a short time period. That is, a time needed to regulate theprocess chamber201 to the predetermined pressure may be shortened. In addition, since the pressure in theprocess chamber201 may be rapidly raised to a comparatively high pressure, the amount of carbon (C) present in theprocess chamber201 may be increased, the amount of carbon (C) added to the first layer may be increased, and the concentration of carbon (C) contained in the first layer may be increased. The second degree of opening means a degree of opening that allows the pressure in theprocess chamber201 to be maintained at a predetermined level and that is automatically adjusted by thecontroller121 as illustrated inFIG. 8. The second exhaust conductance means a conductance that allows the pressure in theprocess chamber201 to be maintained at a predetermined level and that is automatically adjusted by controlling theAPC valve244 via thecontroller121.
• In addition, the degree of opening (first degree of opening) of theAPC valve244 installed at the exhaust line configured to exhaust the inside of theprocess chamber201 is fully closed to suspend controlling of the degree of opening of the APC valve244 (feedback control) when the TEA gas is supplied at the first flow rate, and may be opened to control the degree of opening of theAPC valve244 when the TEA gas is supplied at the second flow rate. That is, the exhaust line configured to exhaust the inside of theprocess chamber201 may be blocked when the TEA gas is supplied at the first flow rate, and may be opened when the TEA gas is supplied at the second flow rate. In this case, a total flow rate of gases supplied into the process chamber201 (i.e., the sum of the flow rates of the TEA gas and the N₂gas) when the TEA gas is supplied at the first flow rate is greater than the exhaust flow rate of a gas exhausted via the exhaust line. In addition, the difference between the total flow rate and the exhaust flow rate is maximized. Thus, the pressure in theprocess chamber201 may be more rapidly raised to be regulated to a predetermined pressure within a shorter time period. That is, a time needed to regulate the pressure in theprocess chamber201 to the predetermined pressure may be shortened more. In addition, since the pressure in theprocess chamber201 may be more rapidly raised to a high pressure, the amount of carbon (C) present in theprocess chamber201 may be increased more, the amount of carbon (C) added to the first layer may be increased more, and the concentration of carbon (C) contained in the first layer may be increased more.
• In addition, the degree of opening (first degree of opening) of theAPC valve244 installed at the exhaust line configured to exhaust the inside of theprocess chamber201 may not be fully closed when the TEA gas is supplied at the first flow rate. For example, theAPC valve244 may be slightly opened to control the degree of opening of theAPC valve244. That is, when the TEA gas is supplied at the first flow rate, a fine gas flow may be formed from the inside of theprocess chamber201 toward thevacuum pump246 by slightly opening the APC valve244 (by extremely reducing (narrowing) the first degree of opening) without adjusting the first exhaust conductance to zero. Even in this case, the total flow rate of gases supplied into theprocess chamber201 may also be adjusted to be greater than the exhaust flow rate of a gas exhausted via the exhaust line. In this case, this state in which the total flow rate of gases supplied into theprocess chamber201 is greater than the exhaust flow rate of gas exhausted via the exhaust line may be caused by controlling flow rate adjustment and pressure regulation by themass flow controllers241band241fand theAPC valve244 through thecontroller121, respectively. In this case, the pressure in theprocess chamber201 may also be rapidly raised to the predetermined pressure and the concentration of carbon (C) contained in the first layer may also be increased. However, the pressure in theprocess chamber201 may be more rapidly raised and the concentration of carbon (C) contained in the first layer may be more increased when the degree of opening (first degree of opening) of theAPC valve244 is fully closed.
• In addition, the pressure in theprocess chamber201 is changed according to a balance between the flow rate of a gas supplied into theprocess chamber201 and the exhaust speed (exhaust conductance) of a gas exhausted by the exhaust line configured to exhaust the inside of theprocess chamber201. Since it may take a time to stabilize this balance, the pressure in theprocess chamber201 may not be raised to the predetermined pressure within a short time period while exhausting is performed using the exhaust line, thereby lowering product yield. In particular, when the flow rate of a gas supplied into theprocess chamber201 is lowered, it may take a time to raise the pressure in theprocess chamber201, thereby greatly lowering product yield. In contrast, according to the first embodiment, when the TEA gas is supplied at the first flow rate, the degree of opening (first degree of opening) of theAPC valve244 installed at the exhaust line is fully closed, theAPC valve244 is slightly opened (first degree of opening is lowered), or the degree of opening (first degree of opening) of theAPC valve244 is set to be less than the second degree of opening. Thus, the pressure in theprocess chamber201 may be raised within a short time period and the film-forming yield may be improved, thereby increasing the concentration of carbon (C) contained in the first layer.
• In addition, N₂gas may be supplied at a third flow rate when the TEA gas is supplied at the first flow rate, and may be supplied at a fourth flow rate that is less than the third flow rate when the TEA gas is supplied at the second flow rate. That is, when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, the flow rate of the N₂gas supplied into theprocess chamber201 may also be lowered. In this case, partial pressure of the TEA gas, i.e., the concentration of the TEA gas in theprocess chamber201, may be prevented from being lowered in theprocess chamber201 after the flow rate of the TEA gas supplied into theprocess chamber201 is lowered. In addition, an actual supply rate of the TEA gas to thewafer200, i.e., the number of TEA molecules supplied to thewafer200, may be suppressed from being reduced. That is, the partial pressure and concentration of the TEA gas and the number of TEA molecules supplied to thewafer200 when the TEA gas is supplied at the first flow rate and the pressure in theprocess chamber201 reaches the predetermined pressure may be maintained constant even after the flow rate of the TEA gas supplied into theprocess chamber201 is lowered. As a result, the amount of carbon (C) added to the first layer, i.e., the concentration of carbon (C) contained in the first layer, may be suppressed from being lowered.
• In addition, in step 2 (TEA gas supply process), i.e., during the first TEA gas supply process and the second TEA gas supply process, the ratio of the flow rate of the TEA gas to that of the N₂gas supplied into theprocess chamber201 is preferably maintained constant. That is, when the flow rates of the TEA gas and the N₂gas supplied into theprocess chamber201 are lowered to the second and fourth flow rates, respectively, the ratio of the first flow rate to the third flow rate and the ratio of the second flow rate to the fourth flow rate are preferably set to be the same. That is, the second flow rate and the fourth flow rate may be set to satisfy (first flow rate:third flow rate=second flow rate:fourth flow rate). In other words, instep 2, the ratio (percentage) of the flow rate of the TEA gas to the sum of the flow rates of the TEA gas and the N₂gas, i.e., the rate of the TEA gas (percentage), is preferably maintained constant. That is, the flow rate of the TEA gas/(the flow rate of the TEA gas+the flow rate of the N₂gas) is preferably maintained constant. That is, when the flow rates of the TEA gas and the N₂gas supplied into theprocess chamber201 are lowered to the second flow rate and the fourth flow rate, respectively, the second flow rate and the fourth flow rate are preferably set to satisfy that (first flow rate/(first flow rate+third flow rate))=(second flow rate/(second flow rate+fourth flow rate)).
• The partial pressure V_T(Pa) of the TEA gas in theprocess chamber201 may be expressed as an equation: VT=[Q_T/(Q_T+Q_N)]×V when the flow rate of the TEA gas supplied into theprocess chamber201 is Q_T(sccm), the flow rate of the N₂gas supplied into theprocess chamber201 is Q_N(sccm), and the total pressure in theprocess chamber201 is V(Pa). Thus, if the flow rates of the TEA gas and the N₂gas supplied into theprocess chamber201 are lowered to the second flow rate and the fourth flow rate, respectively, then the partial pressure V_Tof the TEA gas in theprocess chamber201 is maintained constant when the second flow rate and the fourth flow rate are set to maintain the rate of the TEA gas, i.e., [Q_T/(Q_T+Q_N)], constant. That is, the partial pressure V_Tof the TEA gas in theprocess chamber201 may be maintained constant by maintaining the rate of the TEA gas [=Q_T/(Q_T+Q_N)] constant while maintaining the pressure in theprocess chamber201 at a predetermined pressure V, at least after the pressure in theprocess chamber201 reaches a predetermined pressure V. As a result, an actual supply state of the TEA gas with respect to thewafer200 may be maintained constant both before and after the flow rate of the TEA gas is lowered. That is, the number of TEA molecules supplied to thewafer200 may be maintained constant both before and after the flow rate of the TEA gas is lowered. Accordingly, after the flow rate of the TEA gas is lowered, the amount of carbon (C) added to the first layer, i.e., the concentration of carbon (C) contained in the first layer, may be suppressed from being lowered.
• In addition, in step 2 (TEA gas supply process), the amount of carbon (C) added to the first layer may be changed by changing the ratio of the flow rate of the TEA gas to that of the N₂gas supplied into theprocess chamber201 when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, i.e., by changing the partial pressure in theprocess chamber201. For example, when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, the amount of carbon (C) added to the first layer may be reduced by adjusting the flow rate of the N₂gas to satisfy (fourth flow rate)>(third flow rate)_x(second flow rate)/(first flow rate), i.e., by lowering the partial pressure of the TEA gas in theprocess chamber201 by reducing the rate of the TEA gas. In addition, for example, when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, the amount of carbon (C) added to the first layer may be reduced by adjusting the flow rate of the N₂gas to satisfy (fourth flow rate)<(third flow rate)_x(second flow rate)/(first flow rate), i.e., by increasing the partial pressure of the TEA gas in theprocess chamber201 by increasing the rate of the TEA gas.
• In addition, when the TEA gas is supplied at the first flow rate, the pressure in theprocess chamber201 may be set to fall within, for example, a range of 1 to 13,300 Pa, and preferably, a range of 399 to 3,990 Pa. When the pressure in theprocess chamber201 is set to be comparatively high, the TEA gas may be thermally activated in a non-plasma state. In addition, since the TEA gas may be thermally activated and supplied to cause a soft reaction, the modification described above may be softly performed. The supply flow rate of the TEA gas may be controlled to be within, for example, a range of 200 to 4,000 sccm using by themass flow controller241b. The supply flow rate of the N₂gas may be controlled to be within, for example, a range of 200 to 10,000 sccm using each of themass flow controllers241f,241e, and241g. In this case, the partial pressure of the TEA gas in theprocess chamber201 is controlled to be within a range of 0.02 to 12,667 Pa. A time period in which the thermally activated TEA gas is supplied to thewafer200, i.e., a gas supply time (exposure time), may be, for example, within a range of 6 to 24 seconds. In this case, similar tostep 1, the temperature of theheater207 is set such that the temperature of thewafer200 may be, for example, within a range of 250 to 700° C., preferably, 300 to 650° C., and more preferably, 350 to 600° C.
• When the TEA gas is supplied at the second flow rate, the pressure in theprocess chamber201 may be, for example, within a range of 1 to 13,300 Pa, and preferably, a range of 399 to 3,990 Pa, similar to when the TEA gas is supplied at the first flow rate. The supply flow rate of the TEA gas controlled by themass flow controller241bmay be, for example, within a range of 100 to 2,000 sccm. The supply flow rate of the N₂gas controlled by themass flow controllers241f,241e, and241gmay be, for example, within a range of 100 to 5,000 sccm. In this case, the partial pressure of the TEA gas in theprocess chamber201 may be within a range of 0.02 to 12,667 Pa, similar to when the TEA gas is supplied at the first flow rate. A time period in which the thermally activated TEA gas is supplied to thewafer200, i.e., a gas supply time (exposure time), may be, for example, within a range of 12 to 120 seconds. In this case, similar tostep 1, the temperature of theheater207 is set such that the temperature of thewafer200 may be, for example, within a range of 250 to 700° C., preferably, 300 to 650° C., and more preferably, 350 to 600° C., similar to when the TEA gas is supplied at the first flow rate.
• Remaining Gas Removal
• After the first layer is formed, thevalve243bof the secondgas supply pipe232bis closed and the supply of the TEA gas is suspended. In this case, the inside of theprocess chamber201 is vacuum-exhausted by thevacuum pump246 in a state in which theAPC valve244 of theexhaust pipe231 is opened (preferably, in a state in which theAPC valve244 is fully opened), and either the TEA gas remaining in theprocess chamber201 after non-reaction or contribution to formation of the first layer or reaction byproducts are removed from the inside of theprocess chamber201. In addition, in this case, supply of N₂gas as an inert gas into theprocess chamber201 is maintained while thevalves243f,243e, and243gare opened. The N₂gas serves as a purge gas, and causes either the TEA gas remaining in theprocess chamber201 after non-reaction or contribution to formation of the first layer or the reaction byproducts to be effectively removed from the inside of theprocess chamber201.
• In this case, a gas remaining in theprocess chamber201 may not be completely removed and the inside of theprocess chamber201 may not be completely purged. When a small amount of the gas is remained in theprocess chamber201,step 3 performed afterstep 2 is not badly influenced by this gas. In this case, the flow rate of the N₂gas to be supplied into theprocess chamber201 may not be high. For example, the inside of theprocess chamber201 may be purged by supplying an amount of N₂gas corresponding to the capacity of the reaction tube203 (process chamber201) such thatstep 3 is not badly influenced by this gas. As described above, a purge time may be shortened by not completely purging the inside of theprocess chamber201, thereby improving the throughput. In addition, consumption of the N₂gas may be suppressed to a necessary minimum value.
• As an amine-based gas, not only triethylamine [(C₂H₅)₃N, abbreviated to TEA] but also an ethylamine-based gas obtained by evaporating diethylamine [(C₂H₅)₂NH, abbreviated to DEA], monoethylamine (C₂H₅NH₂, abbreviated to MEA) or the like; a methylamine-based gas obtained by evaporating trimethylamine [(CH₃)₃N, abbreviated to TMA], dimethylamine [(CH₃)₂NH, abbreviated to DMA], monomethylamine (CH₃NH₂, abbreviated to MMA), or the like; a propylamine-based gas obtained by evaporating tripropylamine [(C₃H₇)₃N, abbreviated to TPA], dipropylamine [(C₃H₇)₂NH, abbreviated to DPA], monopropylamine (C₃H₇NH₂, abbreviated to MPA), or the like; an isopropyl amine-based gas obtained by evaporating triisopropylamine [(CH₃)₂CH]₃N, abbreviated to TIPA), diisopropylamine [(CH₃)₂CH]₂NH, abbreviated to DIPA), monoisopropylamine [(CH₃)₂CHNH₂, abbreviated to MIPA), or the like; a butyl-based gas obtained by evaporating tributylamine [(C₄H₉)₃N, abbreviated to TBA], dibutylamine [(C₄H₉)₂NH, abbreviated to DBA], monobutylamine (C₄H₉NH₂, abbreviated to MBA), or the like; or an isobutylamine-based gas obtained by evaporating triisobutylamine [(CH₃)₂CHCH₂]₃N, abbreviated to TIBA), diisobutylamine ([(CH₃)₂CHCH₂]₂NH, abbreviated to DIBA), monoisobutylamine [(CH₃)₂CHCH₂NH₂, abbreviated to MIBA] or the like may be used.
• That is, for example, at least one gas among (C₂H₅)_xNH_3-x, (CH₃)_xNH_3-x, (C₃H₇)_xNH_3-x, [(CH₃)₂CH]_xNH_3-x, (C₄H₉)_xNH_3-x, and [(CH₃)₂CHCH₂]_xNH_3-xmay be preferably used as an amine-based gas. Here, ‘x’ denotes an integer between 1 and 3.
• In addition, as the amine-based gas, a gas consisting of three elements, such as carbon, nitrogen, and hydrogen, and having a composition ratio in which the number of carbon atoms is greater than the number of nitrogen atoms (in one molecule). That is, at least one gas containing an amine selected from the group consisting of TEA, DEA, MEA, TMA, DMA, TPA, DPA, MPA, TIPA, DIPA, MIPA, TBA, DBA, MBA, TIBA, DIBA, and MIBA is preferably used as the amine-based gas.
• If a chlorosilane-based source gas, e.g., the HCDS gas that contains a specific element (silicon) and a halogen element (chlorine), is used as a source gas, then an amine-based gas consisting of three elements, such as carbon, nitrogen, and hydrogen, and having a composition ratio in which the number of carbon elements is greater than the number of nitrogen elements (in one molecule), e.g., the TEA gas or the DEA gas, may be used as the first reactive gas in order to increase the concentration of carbon in the first layer formed instep 2, that is, the concentration of carbon in a SiOCN film or a SiOC film to be formed during a process performed a predetermined number of times (to be described later).
• In contrast, if a chlorosilane-based source gas, e.g., the HCDS gas that contains a specific element (silicon) and a halogen element (chlorine), is used as a source gas, when an amine-based gas, such as MMA gas, or an organic hydrazine-based gas, such as MMH gas or DMH gas consisting of three elements, such as carbon, nitrogen, and hydrogen, and having a composition ratio in which the number of carbon atoms is not greater than the number of nitrogen atoms (in one molecule) (which will be described below), is used as the first reactive gas, then the concentration of carbon in the first layer, i.e., the concentration of carbon in the SiOCN film or the SiOC film, is less than when an amine-based gas consisting of three elements, such as carbon, nitrogen, and hydrogen, and having a composition ratio in which the number of carbon atoms is greater than the number of nitrogen atoms (in one molecule) is used as the first reactive gas. Accordingly, an appropriate concentration of carbon cannot be achieved.
• In addition, a gas having a composition ratio in which a plurality of ligands containing carbon atoms are contained (in one molecule), i.e., a gas having a composition ratio in which a plurality of hydrocarbon groups (e.g., alkyl groups) are contained (in one molecule), is preferably used as an amine-based gas. In detail, a gas having a composition ratio in which two or three ligands (hydrocarbon groups, such as alkyl groups) containing carbon elements are contained (in one molecule), is preferably used as the amine-based gas. For example, at least one gas containing an amine selected from the group consisting of TEA, DEA, TMA, DMA, TPA, DPA, TIPA, DIPA, TBA, DBA, TIBA, and DIBA is preferably used.
• If a chlorosilane-based source gas, such as the HCDS gas containing a specific element (silicon) and a halogen element (chlorine), is used as a source gas, an amine-based gas (such as the TEA gas or the DEA gas) that consists of three elements, such as carbon, nitrogen, and hydrogen, and has a composition ratio in which a plurality of ligands containing carbon atoms are contained (in one molecule), i.e., an amine-based gas having a composition ratio in which a plurality of hydrocarbon groups (alkyl groups) are contained in one molecule, may be used as the first reactive gas in order to increase the concentration of carbon in the first layer, that is, the concentration of carbon in the SiOCN film or the SiOC film.
• In contrast, if a chlorosilane-based source gas, e.g., the HCDS gas that contains a specific element (silicon) and a halogen element (chlorine), is used as a source gas, when an amine-based gas such as MMA gas or an organic hydrazine-based gas such as the MMH gas (which will be described below), which has a composition ratio in which a plurality of ligands containing carbon are not contained (in one molecule) (which will be described below), is used as the first reactive gas, then the concentration of carbon in the first layer, i.e., the concentration of carbon in the SiOCN film or the SiOC film, is less than when an amine-based gas having a composition ratio in which a plurality of ligands containing carbon are contained (in one molecule) is used as the first reactive gas. Accordingly, an appropriate concentration of carbon cannot be achieved.
• In addition, when an amine-based gas (e.g., DEA gas) having a composition ratio in which two ligands containing carbon atoms (hydrocarbon groups such as alkyl groups) are contained (in one molecule) is used as the first reactive gas, a cycle rate (thickness of a SiOCN layer or a SiOC layer formed per unit cycle) may be improved more and the ratio of the concentration of nitrogen to the concentration of carbon (nitrogen concentration/carbon concentration) in the first layer, i.e., the ratio of the concentration of nitrogen to the concentration of carbon (nitrogen concentration/carbon concentration) in the SiOCN film or the SiOC film, may be higher than when an amine-based gas (e.g., TEA gas) having a composition ratio in which three ligands containing carbon atoms (hydrocarbon groups such as alkyl groups) are contained (in one molecule) is used.
• In contrast, when an amine-based gas (e.g., TEA gas) having a composition ratio in which three ligands containing carbon atoms (hydrocarbon groups such as alkyl groups) are contained (in one molecule) is used as the first reactive gas, the ratio of the concentration of carbon to the concentration of nitrogen (carbon concentration/nitrogen concentration) in the first layer, i.e., the ratio of the concentration of carbon to the concentration of nitrogen (carbon concentration/nitrogen concentration) in the SiOCN film or the SiOC film may be higher than when an amine-based gas (e.g., DEA gas) having a composition ratio in which two ligands containing carbon atoms (hydrocarbon groups such as alkyl groups) are contained (in one molecule) is used.
• That is, a cycle rate or the concentration of nitrogen or carbon in the SiOCN film or the SiOC film to be formed may be finely controlled by appropriately adjusting a gas species of the first reactive gas according to the number of ligands containing carbon atoms (the number of hydrocarbon groups such as alkyl groups) in the first reactive gas.
• Gas specifies (composition) of an amine-based gas serving as a first reactive gas may be appropriately selected to increase the concentration of carbon in the SiOCN film or the SiOC film as described above. However, in order to more increase the concentration of carbon, for example, the pressure in theprocess chamber201 when an amine-based gas (TEA gas) is supplied to thewafer200 is preferably higher than the pressure in theprocess chamber201 when a chlorosilane-based source gas (HCDS gas) is supplied to the wafer200 (in step 1), and is preferably higher than the pressure in theprocess chamber201 when an oxygen-containing gas (O₂gas) is supplied to the wafer200 (instep 3 which will be described below). In addition, in this case, the pressure in theprocess chamber201 when the O₂gas is supplied to the wafer200 (in step 3) is preferably higher than the pressure in theprocess chamber201 when the HCDS gas is supplied to the wafer200 (in step 1). That is, if the pressure in theprocess chamber201 when the HCDS gas is supplied to thewafer200 is P₁[Pa], the pressure in theprocess chamber201 when the TEA gas is supplied to thewafer200 is P₂[Pa], and the pressure in theprocess chamber201 when the O₂gas is supplied to the wafer200 P₃[Pa], the pressures P₁to P₃are preferably set to satisfy P₂>P₁, P₃and are more preferably set to satisfy P₂>P₃>P₁. In other words, the pressure in theprocess chamber201 when the TEA gas is supplied to thewafer200 is preferably highest among those insteps 1 to 3.
• In contrast, in order to appropriately suppress an increase in the concentration of carbon in the SiOCN film or the SiOC film, the pressure in theprocess chamber201 when an amine-based gas (TEA gas) is supplied to thewafer200 is preferably less than or equal to the pressure in theprocess chamber201 when an oxygen-containing gas (O₂gas) is supplied to thewafer200 instep 3 or the pressure in theprocess chamber201 when a chlorosilane-based source gas (HCDS gas) is supplied to thewafer200 instep 1. That is, the pressures P₁to P₃are preferably set to satisfy P₃≧P₂or P₃, P₁≧P₂.
• That is, the pressure in theprocess chamber201 when the amine-based gas is supplied may be appropriately controlled to finely adjust the carbon concentration in the SiOCN film or the SiOC film.
• In addition to N₂gas, a rare gas such as Ar gas, He gas, Ne gas, Xe gas, or the like, may be used as the inert gas.
Step 3
• O₂Gas Supply
• Afterstep 2 is terminated and the remaining gas in theprocess chamber201 is removed, thevalve243cof the thirdgas supply pipe232cis opened to cause O₂gas to flow through the thirdgas supply pipe232c. The flow rate of the O₂gas flowing through the thirdgas supply pipe232cis controlled by themass flow controller241c. The flow-rate-controlled O₂gas is supplied into theprocess chamber201 via thegas supply hole250cof thethird nozzle249c. The O₂gas supplied into theprocess chamber201 is thermally activated (excited) to be exhausted through theexhaust pipe231. Here, the thermally activated O₂gas is supplied to thewafer200. Simultaneously, thevalve243gis opened to cause N₂gas to flow through the third inertgas supply pipe232g. The N₂gas is supplied into theprocess chamber201 to be exhausted through theexhaust pipe231 with the O₂gas. In addition, here, in order to prevent invasion of the O₂gas into thefirst nozzle249aand thesecond nozzle249b, thevalves243eand243fare opened to cause the N₂gas to flow through the first inertgas supply pipe232eand the second inertgas supply pipe232f. The N₂gas is supplied into theprocess chamber201 via the firstgas supply pipe232a, the secondgas supply pipe232b, thefirst nozzle249a, and thesecond nozzle249bto be exhausted through theexhaust pipe231.
• Here, theAPC valve244 is appropriately adjusted such that the pressure in theprocess chamber201 is a pressure within a range of, for example, 1 to 3,000 Pa. As the pressure in theprocess chamber201 arrives at such a relatively high pressure, the O₂gas can be thermally activated with non-plasma. In addition, since the O₂gas may be thermally activated to be supplied to generate a soft reaction, oxidation (to be described below) may be softly performed. A supply flow rate of the O₂gas controlled by themass flow controller241cis a flow rate within a range of, for example, 100 to 10,000 sccm. A supply flow rate of the N₂gas controlled by themass flow controllers241g,241eand241fmay be a flow rate within a range of, for example, 100 to 10,000 sccm. Here, a partial pressure of the O₂gas in theprocess chamber201 is a pressure within a range of 0.01 to 2,970 Pa. A time in which the thermally activated O₂gas is supplied to thewafer200, i.e., a gas supply time (exposure time), is a time within a range of for example, 1 to 120 seconds, preferably 1 to 60 seconds. Here, likesteps 1 and 2, the temperature of theheater207 is set such that the temperature of thewafer200 is a temperature within a range of, for example, 250 to 700° C., preferably 300 to 650° C., and more preferably 350 to 600° C.
• Here, the gas flowing into theprocess chamber201 is the O₂gas thermally activated by increasing the pressure in theprocess chamber201, and neither HCDS gas nor TEA gas flows into theprocess chamber201. Accordingly, the O₂gas does not generate a gaseous reaction, and the activated O₂gas reacts with at least a portion of the first layer including Si, N and C formed on thewafer200 instep 2. Accordingly, the first layer is oxidized to be modified as a layer including silicon, oxygen, carbon, and nitrogen, which is a second layer, i.e., a silicon oxycarbonitride layer (SiOCN layer), or a layer including silicon, oxygen and carbon, i.e., a silicon oxycarbide layer (SiOC layer).
• In addition, as the O₂gas is thermally activated to be flowed into theprocess chamber201, the first layer may be thermally oxidized to be modified (changed) into the SiOCN layer or the SiOC layer. Here, an0 component is added to the first layer to modify the first layer into the SiOCN layer or the SiOC layer. In addition, the Si—O bonding in the first layer is increased by an action of the thermal oxidation due to the O₂gas, and the Si—N bonding, Si—C bonding, and Si—Si bonding are reduced to reduce a ratio of an N component, a ratio of a C component, and a ratio of a Si component in the first layer. In addition, here, as the thermal oxidation time is lengthened or an oxidizing power of the thermal oxidation is increased, most of the N component can be desorbed to reduce the N component to an impurity level or substantially remove the N component. That is, the first layer may be modified into the SiOCN layer or the SiOC layer while varying the composition ratio thereof in a direction of increasing the oxygen concentration or in a direction of reducing the nitrogen concentration, the carbon concentration and the silicon concentration. In addition, here, the process conditions such as the pressure in theprocess chamber201, the gas supply time, or the like, may be controlled to finely adjust a ratio of the 0 component in the SiOCN layer or the SiOC layer, i.e., the oxygen concentration, and the composition ratio of the SiOCN layer or the SiOC layer may thus be more finely controlled.
• In addition, it has been confirmed that the C component is richer than the N component in the first layer formed insteps 1 and 2. For example, in an experiment, the carbon concentration was twice the nitrogen concentration or more. That is, as the oxidation is blocked before the N component in the first layer is completely desorbed by an action of the thermal oxidation due to the O₂gas, i.e., in a state in which the N component remains, the C component and the N component remain in the first layer so that the first layer is modified into the SiOCN layer. In addition, the C component remains in the first layer even in a step in which most of the N component in the first layer is desorbed by the action of the thermal oxidation due to the O₂gas, and in this state, the oxidation is blocked so that the first layer is modified into the SiOC layer. That is, the gas supply time (oxidation processing time) or the oxidizing power may be controlled to control a ratio of the C component, i.e., the carbon concentration, and one of the SiOCN layer and the SiOC layer may thus be formed while controlling the composition ratio. In addition, here, the process conditions, such as the pressure in theprocess chamber201, the gas supply time, or the like, may be controlled to finely adjust the ratio of the O component in the SiOCN layer or the SiOC layer, i.e., the oxygen concentration, and the composition ratio of the SiOCN layer or the SiOC layer may thus be more finely controlled.
• In addition, here, it is preferable that the oxidation reaction of the first layer be unsaturated. For example, when the first layer having a thickness of less than one atomic layer to several atomic layers is formed insteps 1 and 2, it is preferable that a portion of the first layer be oxidized. In this case, the oxidation is performed under the conditions in which the oxidation reaction of the first layer is unsaturated such that the entire first layer having a thickness of less than one atomic layer to several atomic layers is not oxidized.
• The process conditions instep 3 may be the above-mentioned process conditions to cause the oxidation reaction of the first layer to be unsaturated, but are set to the following process conditions to cause easy unsaturation of the oxidation reaction of the first layer:
• Wafer temperature: 500 to 650° C.
• Pressure in process chamber: 133 to 2,666 Pa
• O₂gas partial pressure: 33 to 2,515 Pa
• O₂gas supply flow rate: 1,000 to 5,000 sccm
• N₂gas supply flow rate: 300 to 3,000 sccm
• O₂gas supply time: 6 to 60 seconds
• Remaining Gas Removal
• After the second layer is formed, thevalve243cof the thirdgas supply pipe232cis closed to stop supply of the O₂gas. Here, the inside of theprocess chamber201 is vacuum-exhausted by thevacuum pump246 in a state in which theAPC valve244 of theexhaust pipe231 is open (preferably, in a state in which theAPC valve244 is fully open) in order to remove either the O₂gas or the reaction byproduct after non-reaction or contribution to formation of the second layer and remaining in theprocess chamber201 from the inside of theprocess chamber201. In addition, here, supply of the N₂gas into theprocess chamber201 is maintained in a state in which thevalves243g,243e, and243fare open. The N₂gas serves as the purge gas to increase an effect of removing the O₂gas or the reaction byproduct after non-reaction or contribution to formation of the second layer and remaining in theprocess chamber201 from the inside of theprocess chamber201.
• In addition, here, the gas remaining in theprocess chamber201 may not be completely removed, and the inside of theprocess chamber201 may not be completely purged. When the gas remaining in theprocess chamber201 is minute, there is no bad influence instep 1 performed thereafter. Here, a flow rate of the N₂gas supplied into theprocess chamber201 need not be a large flow rate, and for example, an amount of gas substantially equal to a capacity of the reaction tube203 (the process chamber201) may be supplied to perform the purge such that there is no bad influence generated instep 1. As described above, as the inside of theprocess chamber201 is not completely purged, the purge time can be reduced to improve throughput. In addition, consumption of the N₂gas may be suppressed to a necessary minimum value.
• In addition to the O₂gas, nitrous oxide (N₂O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO₂) gas, ozone (O₃) gas, hydrogen (H₂) gas+oxygen (O₂) gas, H₂gas+O₃gas, vapor (H₂O) gas, carbon monoxide (CO) gas, carbon dioxide (CO₂) gas, or the like may be used as the oxygen-containing gas (oxidizing gas). In addition to the N₂gas, a rare gas, such as Ar gas, He gas, Ne gas, Xe gas, or the like, may be used as the inert gas.
• Perform Cycle Predetermined Number of Times
• The above-mentionedsteps 1 to 3 are set as one cycle, and the cycle may be performed a predetermined number of times to form a film including silicon, oxygen, carbon and nitrogen, i.e., a silicon oxycarbonitride (SiOCN) film, or a film including silicon, oxygen and carbon, i.e., a silicon oxycarbide (SiOC) film, which has a predetermined composition and a predetermined film thickness, on thewafer200. The cycle is preferably performed a plurality of times. That is, it is preferable that a thickness of the SiOCN layer or the SiOC layer formed per cycle be set to be smaller than a desired film thickness, and the cycle be performed a plurality of times until the thickness arrives at the desired film thickness.
• When the cycle is performed a plurality of times, the phrase “predetermined gas is supplied to thewafer200” in each step at least after a second cycle means “predetermined gas is supplied to a layer formed on thewafer200, i.e., the outermost surface of thewafer200, which is a stacked structure,” and the phrase “predetermined layer is formed on thewafer200” means “predetermined layer is formed on a layer formed on thewafer200, i.e., the outermost layer of thewafer200, which is a stacked structure.” This is similar to the above-mentioned description. In addition, this will be similar in the following other embodiments.
• Purge and Atmospheric Pressure Recovery
• When film-forming is performed to form a SiOCN film or a SiOC film having a predetermined composition and a predetermined film thickness, thevalves243e,243f, and243gare opened to supply N₂gas serving as an inert gas into theprocess chamber201 via the first inertgas supply pipe232e, the second inertgas supply pipe232f, and the third inertgas supply pipe232gand exhaust the N₂gas via theexhaust pipe231. The N₂gas may also serve as a purge gas, and allows the inside of theprocess chamber201 to be purged with the inert gas, thereby removing a gas or reaction byproducts remaining in theprocess chamber201 from the inside of the process chamber201 (purging). Thereafter, the atmosphere in theprocess chamber201 is substituted with the inert gas (inert gas substitution) to return the pressure in theprocess chamber201 to a normal pressure (atmospheric pressure recovery).
• Boat Unloading and Wafer Discharging
• Then, theseal cap219 is moved downward by theboat elevator115 to open the lower end of thereaction tube203, and at the same time, the processedwafer200 is unloaded from the lower end of thereaction tube203 to the outside of the reaction tube203 (boat unloading) while being supported by theboat217. Then, the processedwafer200 is discharged from the boat217 (wafer discharging).
(3) Effects of the First Embodiment
• According to the first embodiment, one or more of the following effects are provided.
• (a) According to the first embodiment, instep 2, when the TEA gas is supplied, first, the TEA gas is supplied at the first flow rate (first TEA gas supply process). Then, after the pressure in theprocess chamber201 reaches a predetermined pressure, the TEA gas is supplied at the second flow rate that is less than the first flow rate while the predetermined pressure is maintained in the process chamber201 (second TEA gas supply process). Thus, instep 2, a total supply rate of the TEA gas into theprocess chamber201, i.e., the consumption rate of the TEA gas, may be less than when the TEA gas is continuously supplied at the first flow rate into theprocess chamber201. As a result, costs for forming the SiOCN film or the SiOC film may be saved.
• (b) According to the first embodiment, instep 2, theAPC valve244 installed at the exhaust line configured to exhaust the inside of theprocess chamber201 is set to have a first degree of opening when the TEA gas is supplied at the first flow rate, and is set to a second degree of opening that is greater than the first degree of opening when the TEA gas is supplied at the second flow rate that is greater than the first flow rate. That is, the exhaust conductance at the exhaust line configured to exhaust the inside of theprocess chamber201 is set to be a first exhaust conductance when the TEA gas is supplied at the first flow rate, and is set to be a second exhaust conductance that is greater than the first exhaust conductance when the TEA gas is supplied at the second flow rate. In other words, when the TEA gas is supplied at the first flow rate, the degree of opening of theAPC valve244 is preferably set to be the first degree of opening that is less (narrower) than the second degree of opening and the exhaust conductance is preferably set to be the first exhaust conductance that is less than the second first exhaust conductance. In this case, when the TEA gas is supplied at the first flow rate, a total flow rate of gases supplied into the process chamber201 (i.e., the sum of the flow rates of the TEA gas and the N₂gas) is preferably greater than the exhaust flow rate of a gas exhausted via the exhaust line. In this case, the pressure in theprocess chamber201 may be rapidly raised to a predetermined pressure within a short time period. That is, a time needed to equalize the pressure in theprocess chamber201 with the predetermined pressure may be shortened. Since the pressure in theprocess chamber201 can be rapidly raised to a comparatively high pressure, the amount of carbon (C) present in theprocess chamber201 may be increased, the amount of carbon (C) added to the first layer may be increased, and the concentration of carbon (C) contained in the first layer may be increased.
• (c) According to the first embodiment, instep 2, the degree of opening (first degree of opening) of theAPC valve244 installed at the exhaust line configured to exhaust the inside of theprocess chamber201 is fully closed to suspend control of the degree of opening of theAPC valve244 when the TEA gas is supplied at the first flow rate, and is controlled by opening theAPC valve244 when the TEA gas is supplied at the second flow rate. That is, the exhaust line configured to exhaust the inside of theprocess chamber201 is blocked when the TEA gas is supplied at the first flow rate, and is opened when the TEA gas is supplied at the second flow rate. Thus, the pressure in theprocess chamber201 may be more rapidly raised. As a result, a rate and productivity of forming the SiOCN film or the SiOC film may be increased. In addition, since the pressure in theprocess chamber201 may be more rapidly raised to a comparatively high pressure, the amount of carbon present in theprocess chamber201 may be increased, and the concentration of carbon contained in the SiOCN film or the SiOC film may be more increased.
• (d) According to the first embodiment, instep 2, N₂gas is supplied at the third flow rate when the TEA gas is supplied at the first flow rate, and is supplied at the fourth flow rate that is less than the third flow rate when the TEA gas is supplied at the second flow rate. That is, when the flow rate of the TEA gas supplied into theprocess chamber201 is reduced, the flow rate of N₂gas supplied into theprocess chamber201 is also reduced. Thus, after the flow rate of the TEA gas supplied into theprocess chamber201 is reduced, the partial pressure of the TEA gas in theprocess chamber201, i.e., the concentration of the TEA gas in theprocess chamber201, may be suppressed from being lowered. In addition, an actual supply rate of the TEA gas to thewafer200, i.e., the number of TEA molecules supplied to thewafer200, may be suppressed from being reduced. As a result, the amount of carbon (C) added to the SiOCN film or the SiOC film, i.e., the concentration of carbon (C) contained in the SiOCN film or the SiOC film, may be suppressed from being reduced.
• (e) According to the first embodiment, instep 2, the ratio of the flow rate of the TEA gas to that of the N₂gas supplied into theprocess chamber201 is maintained constant. That is, when the flow rates of the TEA gas and the N₂gas supplied into theprocess chamber201 are lowered to the second flow rate and the fourth flow rate, respectively, the second flow rate and the fourth flow rate are set to satisfy (first flow rate:third flow rate=second flow rate:fourth flow rate). Accordingly, at least after the pressure in theprocess chamber201 reaches the predetermined pressure, the partial pressure of the TEA gas in theprocess chamber201 is maintained constant. As a result, an actual supply rate of the TEA gas to thewafer200 may be maintained constant both before and after the flow rate of the TEA gas is reduced. In other words, the number of TEA molecules supplied to thewafer200 may be maintained constant both before and after the flow rate of the TEA gas is reduced. As a result, the amount of carbon (C) added to the SiOCN film or the SiOC film, i.e., the concentration of carbon (C) contained in the SiOCN film or the SiOC film, may be suppressed from being lowered.
• (f) According to the first embodiment, instep 2, when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, the amount of carbon (C) added to the SiOCN film or the SiOC film may be changed by changing the ratio of the flow rate of the TEA gas to that of the N₂gas supplied into theprocess chamber201, i.e., by changing the partial pressure of the TEA gas in theprocess chamber201. For example, when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, the partial pressure of the TEA gas in theprocess chamber201 may be lowered by adjusting the flow rate of the N₂gas to satisfy ((fourth flow rate)>(third flow rate)×(second flow rate)/(first flow rate)), i.e., lowering the rate of the TEA gas, thereby reducing the amount of carbon (C) added to the SiOCN film or the SiOC film. In addition, for example, when the flow rate of the TEA gas supplied into theprocess chamber201 is reduced, the partial pressure of the TEA gas in theprocess chamber201 may be raised by adjusting the flow rate of the N₂gas to satisfy (fourth flow rate)<(third flow rate)×(second flow rate)/(first flow rate), i.e., by increasing the rate of the TEA gas, thereby increasing the amount of carbon (C) added to the first layer.
• (g) According to the first embodiment, a first layer containing Si, N, and C is formed by alternately performingsteps 1 and 2,step 3 may be performed to oxidize the first layer to be modified into a SiOCN layer or a SiOC layer as a second layer by supplying O₂gas (which is an oxygen-containing gas) as a second reactive gas, thereby adjusting a composition ratio among oxygen, carbon, and nitrogen contained in a SiOCN film or a SiOC film. In addition, in this case, O₂gas may be thermally activated and supplied to increase Si—O bonds and reduce Si—C bonds, Si—N bonds, and Si—Si bonds in the SiOCN film or the SiOC film, due to an operation of the thermal oxidization. That is, this composition ratio may be changed in a direction of increasing oxygen concentration and a direction of reducing nitrogen concentration, carbon concentration, and silicon concentration. In addition, in this case, the thermal oxidation time or an oxidizing power of the thermal oxidation may be increased to change this composition ratio in a direction of increasing oxygen concentration more or a direction of reducing nitrogen concentration, carbon concentration, and silicon concentration more. In addition, in this case, a ratio of the oxygen component in the SiOCN film or the SiOC film, i.e., the concentration of oxygen, may be finely controlled by controlling the pressure in theprocess chamber201 or process conditions, e.g., a gas supply time, thereby more finely controlling the composition ratio of the SiOCN film or the SiOC film. Accordingly, the dielectric constant, etching resistance, or insulating properties of the SiOCN film or the SiOC film may be improved.
Second Embodiment of the Present Invention
• Next, a second embodiment of the present invention will be described.
• The first embodiment has been described above with respect to a process of forming a silicon oxycarbonitride film or a silicon oxycarbide film having a predetermined composition and a predetermined film thickness on thewafer200 using an oxygen-containing gas (O₂gas) as a second reactive gas. In contrast, the second embodiment will be described below with respect to a process of forming a silicon carbonitride (SiCN) film having a predetermined composition and a predetermined film thickness on thewafer200 using a nitrogen-containing gas (NH₃gas) as a second reactive gas.
• Specifically, in the second embodiment, an example of a process of forming a silicon carbonitride (SiCN) film having a predetermined composition and a predetermined film thickness on thewafer200 in theprocess chamber201 by performing a cycle a predetermined number of times (n times), the cycle including: a process of forming a silicon-containing layer containing chlorine on thewafer200 in theprocess chamber201 by supplying a chlorosilane-based source gas (HCDS gas) to thewafer200; a process of forming a first layer containing silicon, nitrogen, and carbon by modifying the silicon-containing layer containing chlorine by supplying an amine-based gas (TEA gas) as a first reactive gas to thewafer200 in theprocess chamber201; and a process of forming a SiCN film as a second layer by modifying the first layer by supplying a nitrogen-containing gas (NH₃gas) as a second reactive gas to thewafer200 will be described.
• FIG. 6 is a view showing a film-forming flow according to a second embodiment of the present invention.FIG. 7 is a view showing gas supply timing in a film-forming sequence according to the second embodiment of the present invention. The second embodiment is substantially the same as the first embodiment, except that instep 3, thermally activated NH₃gas is used as a second reactive gas.Step 3 according to the second embodiment will now be described.
Step 3
• NH₃Gas Supply
• Afterstep 2 is terminated and a remaining gas in theprocess chamber201 is removed, thevalve243dof the fourthgas supply pipe232dis opened to cause NH₃gas to flow into the fourthgas supply pipe232d. The flow rate of the NH₃gas flowing through the fourthgas supply pipe232dis adjusted by themass flow controller241d. The flow-rate-adjusted NH₃gas is supplied into theprocess chamber201 via thegas supply hole250cof thethird nozzle249c. The NH₃gas supplied into thefourth process chamber201 is thermally activated (excited), and is exhausted via theexhaust pipe231. In this case, the thermally activated NH₃gas is supplied to thewafer200. Simultaneously, thevalve243gis opened to cause N₂gas to flow into the third inertgas supply pipe232g. The N₂gas is supplied into theprocess chamber201 together with the NH₃gas, and is exhausted via theexhaust pipe231. In this case, in order to prevent invasion of the NH₃gas into thefirst nozzle249aandsecond nozzle249b, thevalves243eand243fare opened to cause the N₂gas to flow into the first inertgas supply pipe232eand the second inertgas supply pipe232f. The N₂gas is supplied into theprocess chamber201 via the firstgas supply pipe232a, the secondgas supply pipe232b, thefirst nozzle249a, and thesecond nozzle249b, and is exhausted via theexhaust pipe231.
• In this case, theAPC valve244 may be appropriately adjusted to regulate the pressure in theprocess chamber201 to be within, for example, a range of 1 to 3,000 Pa. By regulating the pressure in theprocess chamber201 to a comparatively high pressure as described above, the NH₃gas may be thermally activated in a non plasma state. In addition, when the NH₃gas is thermally activated and supplied, a soft reaction may thus occur, thereby softly performing nitridation which will be described below. The supply flow rate of the NH₃gas controlled by themass flow controller241cmay be a flow rate that falls within, for example, a range of 100 to 10,000 sccm. The supply flow rate of the N₂gas controlled by each of themass flow controllers241g,241e, and241fmay be a flow rate that falls within, for example, a range of 100 to 10,000 sccm. In this case, the partial pressure of the NH₃gas in theprocess chamber201 falls within a range of 0.01 to 2,970 Pa. A time in which the thermally activated NH₃gas is supplied to thewafer200, i.e., a gas supply time (exposure time), is within, for example, a range of 1 to 120 seconds, and preferably 1 to 60 seconds. In this case, a temperature of theheater207 is set such that the temperature of thewafer200 is within a range of, for example, 250 to 700° C., preferably 300 to 650° C., and more preferably 350 to 600° C., as insteps 1 and 2.
• In this case, the gas flowing into theprocess chamber201 is the NH₃gas that is thermally activated by increasing the temperature in theprocess chamber201, and neither HCDS gas nor TEA gas flows into theprocess chamber201. Accordingly, the NH₃gas does not cause a gaseous reaction, and the activated NH₃gas reacts with at least a portion of the first layer including Si, N, and C formed on thewafer200 instep 2. Accordingly, the first layer is nitrided to be modified as a layer including silicon, carbon and nitrogen, which is a second layer, i.e., a silicon carbonitride (SiCN) layer.
• In addition, by thermally activating NH₃gas and flowing it into theprocess chamber201, the first layer may be thermally nitrided to be modified (changed) into a SiCN layer. In this case, the first layer is modified into the SiCN layer while increasing an N component in the first layer. In addition, in this case, through an operation of the thermal nitridation due to the NH₃gas, Si—N bonds increase and Si—C bonds and Si—Si bonds decrease in the first layer, thereby lowering the ratio of a C component and a ratio of a Si component in the first layer. That is, the first layer may be modified into the SiCN layer while changing the composition ratio in a direction of increasing nitrogen concentration and a direction of reducing carbon concentration and silicon concentration. In addition, in this case, process conditions, such as the pressure in theprocess chamber201 or the gas supply time, may be controlled to finely adjust a ratio of an N component (i.e., the concentration of nitrogen) in the SiCN layer, thereby more finely controlling the composition ratio of the SiCN layer.
• In this case, the nitridation reaction of the first layer is preferably unsaturated. For example, when the first layer is formed to a thickness of less than one atomic layer to several atomic layers insteps 1 and 2, a portion of the first layer is preferably nitrided. In this case, the nitridation is performed under conditions in which the nitridation reaction of the first layer is unsaturated such that the entire first layer having a thickness of less than one atomic layer to several atomic layers is not nitrided.
• Further, while the process conditions instep 3 may be the above-mentioned process conditions to cause the nitridation reaction of the first layer to be unsaturated, the process conditions instep 3 are set to the following process conditions to easily cause unsaturation of the nitridation reaction of the first layer:
• Wafer temperature: 500 to 650° C.
• Pressure in process chamber: 133 to 2,666 Pa
• NH₃gas partial pressure: 33 to 2,515 Pa
• NH₃gas supply flow rate: 1,000 to 5,000 sccm
• N₂gas supply flow rate: 300 to 3,000 sccm
• NH₃gas supply time: 6 to 60 seconds
• Remaining Gas Removal
• After the second layer is formed, thevalve243dof the fourthgas supply pipe232dis closed to suspend the supply of the NH₃gas. In this case, the inside of theprocess chamber201 is vacuum-exhausted by thevacuum pump246 in a state in which theAPC valve244 of theexhaust pipe231 is open (preferably, in a state in which theAPC valve244 is fully opened) in order to remove the NH₃gas or reaction byproducts after non-reaction or contribution to formation of the second layer and remaining in theprocess chamber201 from the inside of theprocess chamber201. In addition, here, supply of the N₂gas into theprocess chamber201 is maintained in a state in which thevalves243g,243eand243fare open. The N₂gas serves as the purge gas, and thus an effect of removing the O₂gas or the reaction byproduct after non-reaction or contribution to formation of the second layer and remaining in theprocess chamber201 from the inside of theprocess chamber201 can be increased. In addition, in this case, the supply of the N₂gas into theprocess chamber201 is maintained while thevalves243g,243e, and243fare open. The N₂gas serves as a purge gas to increase an effect of removing the NH₃gas or the reaction byproducts after non-reaction or contribution to formation of the second layer and remaining in theprocess chamber201 from the inside of theprocess chamber201.
• In addition, here, the gas remaining in theprocess chamber201 may not be completely removed, and the inside of theprocess chamber201 may not be completely purged. When the gas remaining in theprocess chamber201 is minute, there is no bad influence instep 1 performed thereafter. In this case, the flow rate of the N₂gas supplied into theprocess chamber201 need not be a large flow rate, and for example, an amount of gas substantially equal to a capacity of the reaction tube203 (the process chamber201) may be supplied to perform the purge such that there is no bad influence generated instep 1. As described above, as the inside of theprocess chamber201 is not completely purged, the purge time can be reduced to improve throughput. In addition, consumption of the N₂gas can be suppressed to a necessary minimum value.
• In addition to the NH₃gas, a gas including a compound such as diazene (N₂H₂) gas, hydrazine (N₂H₄) gas, N₃H₈gas, or the like, may be used as a nitrogen-containing gas (nitriding gas). In addition to the N₂gas, a rare gas such as Ar gas, He gas, Ne gas, Xe gas, or the like, may be used as the inert gas.
• Perform Cycle Predetermined Number of Times
• The above-mentionedsteps 1 to 3 are set as one cycle, and the cycle may be performed at least once (a predetermined number of times) to form a film including silicon, carbon and nitrogen, i.e., a silicon carbonitride (SiCN) film, which has a predetermined composition and a predetermined film thickness, on thewafer200. The cycle is preferably performed a plurality of times. That is, it is preferable that a thickness of a SiCN layer formed per cycle be set to be smaller than a desired film thickness, and the cycle be performed a plurality of times until the thickness arrives at the desired film thickness.
• According to the second embodiment, effects similar to those of the first embodiment may be achieved.
• Specifically, instep 2, during supply of TEA gas, the TEA gas is first supplied at a first flow rate and is then supplied at a second flow rate that is less than the first flow rate while maintaining the pressure in theprocess chamber201 at a predetermined pressure after the pressure in theprocess chamber201 reaches thepressure process chamber201. Accordingly, consumption of the TEA gas may be lowered, thereby saving costs for forming the SiCN film.
• In addition, instep 2, the degree of opening of theAPC valve244 installed at the exhaust line configured to exhaust the inside of theprocess chamber201 is set to be a first degree of opening when the TEA gas is supplied at the first flow rate, and is set to be a second degree of opening that is greater than the first degree of opening when the TEA gas is supplied at the second flow rate that is greater than the first flow rate. Thus, the pressure in theprocess chamber201 may be rapidly raised to the predetermined pressure within a short time period, and the amount of carbon (C) present in theprocess chamber201 may increase, thereby increasing the concentration of carbon (C) contained in the first layer.
• In addition, instep 2, the degree of opening (first degree of opening) of theAPC valve244 installed at the exhaust line configured to exhaust the inside of theprocess chamber201 is fully closed to suspend control of the degree of opening of the APC valve244 (to block the exhaust line) when the TEA gas is supplied at the first flow rate, and theAPC valve244 is opened to perform control of the degree of opening of the APC valve244 (to open the exhaust line) when the TEA gas is supplied at the second flow rate. Thus, the pressure in theprocess chamber201 may be rapidly raised, thereby improving the productivity of forming the SiCN film. In addition, the concentration of carbon (C) contained in the SiCN film may be increased.
• In addition, instep 2, the N₂gas is supplied at a third flow rate when the TEA gas is supplied at the first flow rate, and is supplied at a fourth flow rate that is less than the third flow rate when the TEA gas is supplied at the second flow rate, thereby preventing a decrease in the partial pressure of the TEA gas in theprocess chamber201 and suppressing the concentration of carbon (C) contained in the SiCN film from being lowered.
• In addition, instep 2, a ratio of the flow rate of the TEA gas to that of the N₂gas supplied into theprocess chamber201 is maintained constant to maintain the partial pressure of the TEA gas in theprocess chamber201 constant, thereby suppressing the concentration of carbon (C) contained in the SiCN film from being lowered.
• In addition, instep 2, when the flow rate of the TEA gas supplied into theprocess chamber201 is lowered, the concentration of carbon (C) added to the SiCN film may be changed by changing the ratio of the flow rate of the TEA gas to that of the N₂gas supplied into theprocess chamber201.
• In addition, according to the second embodiment, after the first layer containing Si, N, and C is formed by alternately performingsteps 1 and 2,step 3 is performed to supply NH₃gas (which is a nitrogen-containing gas) as a second reactive gas to nitrate the first layer to be modified into a SiCN layer as a second layer, thereby adjusting a composition ratio of carbon to nitrogen contained in the SiCN film. In addition, in this case, the NH₃gas may be thermally activated and supplied to increase Si—N bonds and reduce Si—C bonds and Si—Si bonds in the SiOCN film or the SiOC film, due to an operation of the thermal nitridation. That is, the composition ratio may be changed in a direction of increasing nitrogen concentration and a direction of reducing carbon concentration and silicon concentration. In addition, in this case, a ratio of a nitrogen component (i.e., the concentration of nitrogen) in the SiCN film may be finely controlled by controlling the pressure in theprocess chamber201 or process conditions, e.g., a gas supply time, thereby more finely controlling the composition ratio of the SiCN film. Accordingly, the dielectric constant, etching resistance, or insulating properties of the SiCN film or the SiOC film may be improved.
Other Embodiments of the Present Invention
• While the present invention has been particularly described with reference to exemplary embodiments thereof, the present invention is not limited thereto and various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
• For example, although in the previous embodiments, a process of changing the flow rate of TEA gas in two steps so as to form a thin film on thewafer200 has been described above, the present invention is not limited thereto. That is, the flow rate of the TEA gas may be changed in three steps or four steps, i.e., multi-steps, to form a thin film on thewafer200. In this case, after the pressure in theprocess chamber201 becomes a predetermined pressure, the degree of opening of theAPC valve244 may also be controlled to maintain the pressure in theprocess chamber201 at the predetermined pressure, and the flow rate of N₂gas may also be controlled to maintain the partial pressure of the TEA gas in theprocess chamber201 at a constant level, thereby obtaining the effects of the previous embodiments.
• In addition, although, according to the previous embodiments, for example, the flow rate of the TEA gas is changed in two steps so as to form a thin film on thewafer200, the present invention is not limited thereto. That is, a thin film may be formed on thewafer200 by changing the flow rate of a source gas, e.g., HCDS gas, in two steps, changing the flow rate of an oxygen-containing gas, e.g., O₂gas, in two steps, or changing the flow rate of a nitrogen-containing gas, e.g., NH₃gas, in two steps. That is, during not only a process of supplying the first reactive gas (amine-based gas) but also a process of supplying a source gas or a process of supplying a second reactive gas (oxygen-containing gas or nitrogen-containing gas), a first supply process of supplying the source gas or the second reactive gas, which is to be used during a present process, at the first flow rate in a state in which exhausting of the inside of theprocess chamber201 is suspended, until the pressure in theprocess chamber201 becomes the same as a predetermined pressure; and a second supply process of supplying the source gas or the second reactive gas, which is to be used during a present process, at the second flow rate (which is less than the first flow rate) while maintaining the pressure in theprocess chamber201 at the predetermined pressure after the pressure in theprocess chamber201 reaches the predetermined pressure, in a state in which the inside of theprocess chamber201 is exhausted may be performed.FIG. 9 illustrates an example of a process of forming a SiOCN film or a SiOC film on thewafer200 while changing the flow rates of a source gas (HCDS gas), a first reactive gas (TEA gas), and an oxygen-containing gas (O₂gas) in two steps. However, since a carbon-containing gas which is a carbon source, such as TEA gas, is comparatively expensive compared to an oxygen-containing gas or a nitrogen-containing gas and the concentration of carbon (C) in a thin film is comparatively difficult to increase, it is possible to achieve remarkable effects of the present invention when a thin film is formed on thewafer200 while changing the flow rate of the carbon-containing gas which is a carbon source in two steps.
• In addition, although in the previous embodiments, for example, when the first layer containing Si, N, and C is formed, the chlorosilane-based source gas and the amine-based gas are sequentially supplied to thewafer200 in theprocess chamber201, the order of supplying these gases may be reversed. That is, the amine-based gas may be supplied and then the chlorosilane-based source gas may be supplied. In other words, one of the chlorosilane-based source gas and the amine-based gas may be supplied and the other may then be supplied. By reversing the order of supplying these gases as described above, a film quality or composition ratio of a thin film to be formed may be changed.
• In addition, although in the previous embodiments, for example, during the process of forming the first layer, the first layer containing Si, N, and C is formed by alternately performingsteps 1 and 2, the first layer containing Si, N, and C may be formed by alternately performingsteps 1 and 2 a predetermined number of times. That is, during the process of forming the first layer, the first layer containing Si, N, and C may be formed by alternately performingsteps 1 and 2 a predetermined number of times (at least once). Specifically, in the first embodiment, a SiOCN film or a SiOC film may be formed on thewafer200 by performing a cycle a predetermined number of times, the cycle including a process of forming the first layer containing Si, N, and C by alternately performingsteps 1 and 2 a predetermined number of times (at least once), and a process of oxidizing the first layer to form a SiOCN layer or a SiOC layer as a second layer by supplying an oxygen-containing gas as a second reactive gas. In the second embodiment, a SiCN film may be formed on thewafer200 by performing a cycle a predetermined number of times, the cycle including a process of forming the first layer containing Si, N, and C by alternately performingsteps 1 and 2 a predetermined number of times (at least once), and a process of nitrating the first layer to form a SiCN layer as a second layer by supplying a nitrogen-containing gas as a second reactive gas.
• In addition, although in the previous embodiments, for example, instep 1, when a seed layer containing a specific element (silicon) and a halogen element (chlorine) is formed using a chlorosilane-based source gas is used as a source gas, a silane-based source gas having halogen-based ligands other than chloro groups may be used instead of the chlorosilane-based source gas. For example, a fluorosilane-based source gas may be used instead of the chlorosilane-based source gas. Here, the fluorosilane-based source gas refers to a fluorosilane-based source material in a gaseous state, for example, a gas obtained by evaporating a fluorosilane-based source material in a liquid state under a normal temperature and a normal pressure, or a fluorosilane-based source material in a gaseous state under a normal temperature and a normal pressure. In addition, the fluorosilane-based source material refers to a silane-based source material including a fluoro group serving as a halogen group, i.e., a source material including at least silicon (Si) and fluorine (F). That is, here, the fluorosilane-based source material may be referred to as a halide. For example, a silicon fluoride gas such as tetrafluorosilane, i.e., silicontetrafluoride (SiF₄) gas, hexafluorodisilane (Si₂F₆) gas, or the like, may be used as the fluorosilane-based source gas. In this case, when the seed layer including a prescribed element and a halogen element is formed, the fluorosilane-based source gas is supplied to thewafer200 in the processing container. In this case, the seed layer is a layer including Si and F, i.e., a silicon-containing layer including F.
• In addition, for example, in the previous embodiments, while the example in which the amine-based gas is used as the first reactive gas when the silicon-containing layer including Cl serving as the seed layer is changed (modified) into the first layer including Si, N and C has been described, for example, a gas including an organic hydrazine compound, i.e., an organic hydrazine-based gas, may be used as the first reactive gas, instead of the amine-based gas. In addition, the gas including the organic hydrazine compound may be simply referred to as an organic hydrazine compound gas or an organic hydrazine gas. Here, the organic hydrazine-based gas refers to an organic hydrazine in a gaseous state, for example, a gas obtained by evaporating an organic hydrazine in a liquid state under a normal temperature and a normal pressure, or a gas including a hydrazine group such as organic hydrazine in a gaseous state under a normal temperature and a normal pressure. The organic hydrazine-based gas is a gas composed of three elements of carbon (C), nitrogen (N) and hydrogen (H) and containing no silicon, or a gas containing no silicon and no metal. For example, a methylhydrazine-based gas obtained by evaporating monomethylhydrazine [(CH₃)HN₂H₂, abbreviated to MMH], dimethylhydrazine [(CH₃)₂N₂H₂, abbreviated to DMH], trimethylhydrazine [(CH₃)₂N₂(CH₃)H, abbreviated to TMH], or the like, or an ethylhydrazine-based gas obtained by evaporating ethylhydrazine [(C₂H5)HN₂H₂, abbreviated to EH] or the like may be used as the organic hydrazine-based gas. In this case, the organic hydrazine-based gas is supplied to thewafer200 in the processing container when the silicon-containing layer including Cl is changed (modified) into the first layer including Si, N and C.
• In addition, in the previous embodiments, while the example in which the SiOCN film or the SiOC film is formed on thewafer200 using a source gas, an amine-based gas, or an oxygen-containing gas or the example in which the SiCN film is formed on thewafer200 using a source gas, an amine-based gas, or a nitrogen-containing gas has been described, the present invention is not limited thereto.
• For example, even when a SiOCN film or a SiOC film is formed on thewafer200 using a source gas, an amine-based gas, a carbon-containing gas, and an oxygen-containing gas, or when a SiCN film is formed on thewafer200 using a source gas, an amine-based gas, a carbon-containing gas, and a nitrogen-containing gas, the present invention may be applied thereto. That is, the present invention may be applied to a case in which a cycle including a source gas supply process, an amine-based gas supply process, a carbon-containing gas supply process, and an oxygen-containing gas supply process is performed a predetermined number of times to form a SiOCN film or a SiOC film on thewafer200, or a case in which a cycle including a source gas supply process, an amine-based gas supply process, a carbon-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a SiCN film on thewafer200.
• In addition, for example, the present invention may be applied to a case in which a SiCN film is formed on thewafer200 using a source gas and an amine-based gas or a case in which a SiCN film is formed on thewafer200 using a source gas, an amine-based gas, and a carbon-containing gas. That is, the present invention may also be applied to a case in which a cycle including a source gas supply process and an amine-based gas supply process is performed a predetermined number of times to form a SiCN film on thewafer200 or a case in which a cycle including a source gas supply process, an amine-based gas supply process, and a carbon-containing gas supply process is performed a predetermined number of times to form a SiCN film on thewafer200.
• In addition, the present invention may be applied to a case in which a silicon boron carbonitride (SiBCN) film is formed on thewafer200 using a source gas, an amine-based gas, and a boron-containing gas, a case in which a SiBCN is formed on thewafer200 using a source gas, an amine-based gas, a boron-containing gas, a carbon-containing gas, and a nitrogen-containing gas, or a case in which a silicon boronitride (SiBN) film is formed on thewafer200 using a source gas, an amine-based gas, a boron-containing gas, and a nitrogen-containing gas. That is, the present invention may also be applied to a case in which a cycle including a source gas supply process, an amine-based gas supply process, and a boron-containing gas supply process is performed a predetermined number of times to form a SiBCN film on thewafer200, a case in which a cycle including a source gas supply process, an amine-based gas supply process, a boron-containing gas supply process, a carbon-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a SiBCN film on thewafer200, or a case in which a cycle including a source gas supply process, an amine-based gas supply process, a boron-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a SiBN film on thewafer200.
• In addition, the present invention may be applied to a case in which a boron carbonitride (BCN) film is formed on thewafer200 using a boron-containing gas and an amine-based gas, a case in which a BCN film is formed on thewafer200 using a boron-containing gas, an amine-based gas, a carbon-containing gas, and a nitrogen-containing gas, or a case in which a boron nitride (BN) film is formed on thewafer200 using a boron-containing gas, an amine-based gas, and a nitrogen-containing gas. That is, the present invention may also be applied to a case in which a cycle including a boron-containing gas supply process and an amine-based gas supply process is performed a predetermined number of times to form a BCN film on thewafer200, a case in which a cycle including a boron-containing gas supply process, an amine-based gas supply process, a carbon-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a BCN film on thewafer200, or a case in which a cycle including a boron-containing gas supply process, an amine-based gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a BN film on thewafer200.
• In this case, for example, a hydrocarbon-based gas, such as acetylene (C₂H₂) gas, propylene (C₃H₆) gas, or ethylene (C₂H₄) gas, may be used as the carbon-containing gas. In addition, for example, an inorganic gas such as boron trichloride (BCl₃) gas or diborane (B₂H₆) gas, or an organic gas such as a borazine-based gas (hereinafter referred to as an organic borazine compound) may be used as the boron-containing gas. As the source gas, the amine-based gas, the oxygen-containing gas, and the nitrogen-containing gas may be the same as those in the previous embodiments. In addition, in this case, process conditions may be the same as those in the previous embodiments.
• Furthermore, in this case, during the amine-based gas supply process, the flow rate of the amine-based gas may be changed in two steps as described above. The flow rates of other gases (the source gas, the boron-containing gas, the carbon-containing gas, the oxygen-containing gas, and nitrogen-containing gas) may be changed in two steps as described above. However, since the amine-based gas or the carbon-containing gas which is a carbon source, e.g., C₃H₆gas, is comparatively expensive compared to the oxygen-containing gas or the nitrogen-containing gas and the concentration of carbon (C) in a thin film is comparatively difficult to increase, it is possible to achieve remarkable effects of the present invention when a thin film is formed on thewafer200 while changing the flow rate of the amine-based gas or the flow rate of the carbon-containing gas in two steps. In addition, since the organic borazine compound gas is comparatively expensive, it is also possible to achieve remarkable effects of the present invention when a thin film is formed on thewafer200 while changing the flow rate of the organic borazine compound gas used as the boron-containing gas.
• As described above, the present invention may be preferably applied to an entire substrate processing process using a source gas and an amine-based gas.
• In addition, the present invention may be applied to, for example, a case in which a SiCN film is formed on thewafer200 using a source gas and an aminosilane-based source gas, or a case in which a SiBCN film or a SiBN film having a borazine annular skeleton is formed on thewafer200 using a source gas and an organic borazine compound gas. That is, the present invention may be applied to a case in which a SiCN film is formed on thewafer200 by performing a cycle including a source gas supply process and an aminosilane-based source gas supply process a predetermined number of times, or a case in which a SiBCN film or a SiBN film having a borazine annular skeleton is formed on thewafer200 by performing a cycle including a source gas supply process and an organic borazine compound gas supply process a predetermined number of times.
• In this case, for example, trisdimethylaminosilane (Si[N(CH₃)₂]₃H, abbreviated to 3DMAS) or the like may be used as the aminosilane-based source gas. Further, for example, n,n′,n″-trimethylborazine (abbreviated to TMB) or the like may be used as the organic borazine compound gas. The source gas in the previous embodiments may be used as the source gas. In this case, process conditions may be, similar to, for example, those of the above-mentioned embodiment.
• In addition, in this case, during the aminosilane-based source gas supply process, the flow rate of the aminosilane-based source gas may be changed in two steps as described above. During the organic borazine compound gas supply process, the flow rate of the organic borazine compound gas may be changed in two steps as described above. During the source gas supply process, the flow rate of the source gas may be changed in two steps as described above. However, since the aminosilane-based source gas or the organic borazine compound gas is comparatively expensive, it is possible to achieve remarkable effects of the present invention when a thin film is formed on thewafer200 while changing the flow rates of these gases in two steps.
• As described above, the present invention may be applied to a substrate processing process using the source gas and the aminosilane-based gas or a substrate processing process using the source gas and the organic borazine compound gas.
• In addition, in the previous embodiments, the example in which an amine-based gas which is a gas containing carbon and nitrogen (carbon- and nitrogen-containing gas) is used as a reactive gas has been described above, but the present invention is not limited thereto. For example, the present invention may also be applied to a case in which two types of gases, e.g., a carbon-containing gas and a nitrogen-containing gas, are used as a reactive gas, instead of the amine-based gas.
• For example, the present invention may also be applied to a case in which a cycle including a source gas supply process, a carbon-containing gas supply process, a nitrogen-containing gas supply process, and an oxygen-containing gas supply process is performed a predetermined number of times to form a SiOCN film on thewafer200, or a case in which a cycle including a source gas supply process, a carbon-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a SiCN film on thewafer200. In this case, a hydrocarbon-based gas, such as propylene (C₃H₆) gas, acetylene (C₂H₂) gas, or ethylene (C₂H₄) gas, may be used as the carbon-containing gas, and the nitrogen-containing gas according to the second embodiment described above may be used as the nitrogen-containing gas.
• Furthermore, the present invention may also be applied to a case in which a cycle including a source gas supply process, a carbon-containing gas supply process, a boron-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a SiBCN film on thewafer200. In this case, the carbon-containing gas, the boron-containing gas, and the nitrogen-containing gas are as described above.
• In addition, the present invention may also be applied to a case in which a cycle including a boron-containing gas supply process, a carbon-containing gas supply process, and a nitrogen-containing gas supply process is performed a predetermined number of times to form a BCN film on thewafer200, or a case in which a cycle including a boron-containing gas supply process and a nitrogen-containing gas supply process is performed a predetermined number of times to form a BN film on thewafer200. In this case, the boron-containing gas, the carbon-containing gas, and the nitrogen-containing gas are as described above.
• In this case, during the carbon-containing gas supply process, the flow rate of the carbon-containing gas may be changed in two steps as described above, and the flow rates of other gases (the source gas, the oxygen-containing gas, the nitrogen-containing gas, and boron-containing gas) may be changed in two steps as described above. However, since a carbon-containing gas which is a carbon source, such as C₃H₆gas, is comparatively expensive compared to an oxygen-containing gas or a nitrogen-containing gas and the concentration of carbon (C) in a thin film is comparatively difficult to increase, it is possible to achieve remarkable effects of the present invention when a thin film is formed on thewafer200 while changing the flow rate of the carbon-containing gas which is a carbon source in two steps.
• As described above, the present invention may be preferably applied to a case in which a thin film is formed using a reactive gas, such as a source gas and carbon-containing gas.
• When a silicon-based insulating film or a boron-based insulating film formed by the methods according to the previous embodiments and modified examples thereof is used as a sidewall spacer, a device-forming technique having a small leak current and good machinability can be provided.
• When a silicon-based insulating film or a boron-based insulating film formed by the methods according to the previous embodiments and modified examples thereof is used as an etching stopper, a device-forming technique having good machinability can be provided.
• According to the previous embodiments or modified examples thereof, a silicon-based insulating film or a boron-based insulating film having an ideal stoichiometric ratio can be formed without using plasma even in a low temperature region. In addition, since the silicon-based insulating film or the boron-based insulating film can be formed without using plasma, it may be applied to a process in which plasma damage may occur, for example, a process of forming an SADP film of DPT.
• In addition, although in the previous embodiments, the example in which the silicon-based insulating layer (the SiOCN film, the SiOC film, and the SiCN film) including silicon (which is a semiconductor element) serving as an oxycarbonitride film, an oxycarbide film, or a carbonitride film has been described, the present invention may be applied to a case in which a metal-based thin film including a metal element, such as titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), aluminum (Al), molybdenum (Mo), etc., is formed.
• That is, the present invention may be preferably applied to a case in which a metal oxycarbonitride film, such as a titanium oxycarbonitride (TiOCN) film, a zirconium oxycarbonitride (ZrOCN) film, a hafnium oxycarbonitride (HfOCN) film, a tantalum oxycarbonitride (TaOCN) film, an aluminum oxycarbonitride (AlOCN) film, a molybdenum oxycarbonitride (MoOCN) film, etc. is formed.
• In addition, for example, the present invention may be applied to a case in which a metal oxycarbide film, such as a titanium oxycarbide (TiOC) film, a zirconium oxycarbide (ZrOC) film, a hafnium oxycarbide (HfOC) film, a tantalum oxycarbide (TaOC) film, an aluminum oxycarbide (AlOC) film, a molybdenum oxycarbide (MoOC) film, etc. is formed.
• Further, for example, the present invention may be applied to a case in which a metal carbonitride film, such as a titanium carbonitride (TiCN) film, a zirconium carbonitride (ZrCN) film, a hafnium carbonitride (HfCN) film, a tantalum carbonitride (TaCN) film, an aluminum carbonitride (AlCN) film, a molybdenum carbonitride (MoCN) film, etc. is formed.
• In this case, the film-forming may be performed in a sequence similar to that of any of the previous embodiments using a source gas including a metal element and a halogen element, instead of the chlorosilane-based source gas as in the previous embodiments. That is, a metallic thin film may be formed on thewafer200 in theprocess chamber201 by performing a cycle a predetermined number of times, the cycle including a process of supplying a source gas including a metal element and a halogen element to thewafer200 in theprocess chamber201 and a process of supplying a reactive gas to thewafer200.
• Specifically, a metal-based thin film (a metal oxycarbonitride film, a metal oxycarbide film, or a metal carbonitride film) having a predetermined composition and a predetermined film thickness may be formed on thewafer200 by performing a cycle a predetermined number of times, the cycle including: a process of forming a first layer including a meal element, nitrogen, and carbon on thewafer200 by alternately performing a process of supplying a source gas including a metal element and a halogen element to thewafer200 in theprocess chamber201 and a process of supplying a first reactive gas to thewafer200 in the process chamber201apredetermined number of times; and a process of forming a second layer by supplying a second reactive gas, which is different from the source gas and the first reactive gas, to thewafer200 in theprocess chamber201 to modify the first layer.
• In this case, for example, the flow rate of the first reactive gas is changed in two steps as described above during the process of supplying the first reactive gas. In addition, during the process of supplying the source gas or the process of supplying the second reactive gas, the flow rate of the source gas or the second reactive gas may be changed in two steps as described above.
• For example, when a metal-based thin film (a TiOCN film, a TiOC film, or a TiCN film) including Ti is formed, a gas including Ti and a chloro group such as titanium tetrachloride (TiCl₄) or a gas including Ti and a fluoro group such as titanium tetrafluoride (TiF₄) or the like may be used as a source gas. Gases similar to those of the previous embodiments may be used as the first and second reactive gases. In this case, process conditions may be, for example, similar to those of the above-mentioned embodiment.
• In addition, for example, when a metal-based thin film (a ZrOCN film, a ZrOC film, or a ZrCN film) including Zr is formed, a gas including Zr and a chloro group such as zirconium tetrachloride (ZrCl₄) or the like, or a gas including Zr and a fluoro group such as zirconium tetrafluoride (ZrF₄) or the like may be used as the source gas. Gases similar to those of the previous embodiments may be used as the first and second reactive gases. In this case, process conditions may be, for example, similar to those of the above-mentioned embodiment.
• Further, for example, when a metal-based thin film (a HfOCN film, a HfOC film, or a HfCN film) including Hf is formed, a gas including Hf and a chloro group such as hafnium tetrachloride (HfCl₄) or the like, or a gas including Hf and a fluoro group such as hafnium tetrafluoride (HfF₄) or the like may be used as the source gas. Gases similar to those of the previous embodiments may be used as the first and second reactive gases. In this case, process conditions may be, for example, similar to those of the above-mentioned embodiment.
• In addition, for example, when a metal-based thin film (a TaOCN film, a TaOC film, or a TaCN film) including Ta is formed, a gas including Ta and a chloro group such as tantalum pentachloride (TaCl₅) or the like, or a gas including Ta and a fluoro group such as tantalum pentafluoride (TaF₅) or the like may be used as the source gas. Gases similar to those of the previous embodiments may be used as the first and second reactive gases. In this case, process conditions may be, for example, similar to those of the above-mentioned embodiment.
• In addition, for example, when a metal-based thin film (an AlOCN film, an AlOC film, or an AlCN film) including Al is formed, a gas including Al and a chloro group such as aluminum trichloride (AlCl₃) or the like, or a gas including Al and a fluoro group such as aluminum trifluoride (AlF₃) or the like may be used as the source gas. Gases similar to those of the previous embodiments may be used as the first and second reactive gases. In this case, process conditions may be, for example, similar to those of the above-mentioned embodiment.
• In addition, for example, when a metal-based thin film (a MoOCN film, a MoOC film, or a MoCN film) including Mo is formed, a gas including Mo and a chloro group such as molybdenum pentachloride (MoCl₅) or the like, or a gas including Mo and a fluoro group such as molybdenum pentafluoride (MoF₅) or the like may be used as the source gas. Gases similar to those of the previous embodiments may be used as the first and second reactive gases. In this case, process conditions may be, for example, similar to those of the above-mentioned embodiment.
• That is, the present invention may also be preferably applied to a case in which a thin film having a specific element, such as a semiconductor element or a metal element, is formed.
• A plurality of process recipes (programs each storing a process sequence or process conditions) that are used to form various thin films are preferably prepared according to the details of substrate processing (film type, composition ratio, film quality, film thickness, etc. of the thin film to be formed). When substrate processing starts, an appropriate process recipe is preferably selected among the plurality of process recipes, according to the details of substrate processing. Specifically, the plurality of process recipes that are individually prepared according to the details of substrate processing are preferably stored (installed) beforehand in thememory device121cincluded in the substrate processing apparatus via an electrical communication line or a non-transitory computer-readable recording medium on which the process recipes are recorded (external memory device123). In addition, when substrate processing starts, theCPU121aincluded in the substrate processing apparatus preferably appropriately selects a process recipe matching the details of substrate processing among the plurality of recipes stored in thememory device121c. By configuring the plurality of process recipes as described above, thin films having various film types, composition ratios, film qualities, and film thicknesses may be generally and reproducibly formed using one substrate processing apparatus. Furthermore, load on an operator's manipulation (for example, when a processing sequence or process conditions are input) may be reduced, and substrate processing may be rapidly started without causing errors in manipulation.
• However, the plurality of process recipes described above are not limited to new ones, and may be prepared by, for example, modifying process recipes installed in the substrate processing apparatus. When a process recipe is modified, the modified process recipe may be installed in the substrate processing apparatus via an electrical communication line or a non-transitory computer-readable recording medium on which the process recipes are recorded. Otherwise, the existing process recipes installed in the substrate processing apparatus may be directly changed by manipulating the I/O device122 included in the substrate processing apparatus.
• In the previous embodiments, while the case in which the thin film is formed using the batch type substrate processing apparatus for processing a plurality of substrates at a time has been described, the present invention is not limited thereto and may be applied to the case in which the thin film is formed using a single wafer type substrate processing apparatus for processing one or a plurality of substrates at a time. In addition, in the previous embodiments, while the example in which the thin film is formed using the substrate processing apparatus including the hot wall type processing furnace has been described, the present invention is not limited thereto and may be applied to a case in which a thin film is formed using the substrate processing apparatus including a cold wall type processing furnace.
• The previous embodiments may be appropriately combined and used.
EXAMPLES
• As an example of the present invention, a SiOCN film was formed on a wafer according to the film-forming sequence according to the first embodiment described above. In addition, in a first TEA gas supply process instep 2, the flow rate (first flow rate) of TEA gas was set to be within a range of 200 to 1,000 sccm and a gas supply time was set to be within a range of 10 to 20 seconds. In addition, in a second TEA gas supply process, the flow rate (second flow rate) of the TEA gas was set to be within a range of 100 to 500 sccm and a gas supply time was set to be within a range of 20 to 100 seconds. The other film-forming conditions (process conditions in each step) were the same as those in the first embodiment.
• According to a comparative example, a SiOCN film was formed on a wafer without changing the flow rate of TEA gas supplied into a process chamber in the film-forming sequence according to the first embodiment. In addition, in step 2 (TEA gas supply process), the flow rate of the TEA gas was set to be within a range of 200 to 1,000 sccm and a gas supply time was set to be within a range of 30 to 120 seconds. The other film-forming conditions (process conditions in each step) were the same as those in the first embodiment. As a result, in both the film-forming sequence according to the example of the present invention and the film-forming sequence according to the comparative example, a SiOCN film having about 10 to 20% of carbon concentration was also formed. In addition, in the film-forming sequence according to the example of the present invention, a total supply rate (consumption rate) of the TEA gas was less and a film-forming rate was higher, compared to the film-forming sequence according to the comparative example. In addition, in the film-forming sequence according to the example of the present invention, the total supply rate of the TEA gas was reduced to 60 to 70% of that in the film-forming sequence according to the comparative example.
• According to the present invention, a method of manufacturing a semiconductor device, which is capable of reducing a total supply rate of reactive gases without lowering the concentrations of, for example, oxygen, nitrogen, and carbon contained in a thin film, a substrate processing apparatus, and a non-transitory computer-readable recording medium.
Exemplary Embodiments of the Present Invention
• Exemplary embodiments of the present invention will now be supplementarily stated.
Supplementary Note 1
• According to an embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, including: forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the steps (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
Supplementary Note 2
• In the method ofSupplementary Note 1, the step (c) may include setting a degree of opening of an exhaust valve installed at an exhaust line configured to exhaust the inside of the process chamber to a fully closed state, and the step (d) may include opening the exhaust valve.
Supplementary Note 3
• In the method ofSupplementary Note 1 or 2, the step (c) may include suspending control of a degree of opening of an exhaust valve installed at an exhaust line configured to exhaust the inside of the process chamber, and the step (d) may include performing the control of the degree of opening of the exhaust valve.
Supplementary Note 4
• In the method ofSupplementary Note 3, the step (c) may include setting the degree of opening of the exhaust valve to a fully closed state.
Supplementary Note 5
• In the method ofSupplementary Note 1, the step (c) may include blocking an exhaust line configured to exhaust the inside of the process chamber, and the step (d) may include opening the exhaust line.
Supplementary Note 6
• In the method ofSupplementary Note 1 or 5, each of the steps (c) and (d) may include supplying an inert gas together with the source gas or the reactive gas.
Supplementary Note 7
• In the method of Supplementary Note 6, each of the steps (c) and (d) may include maintaining a ratio of a flow rate of the source gas or the reactive gas to that of the inert gas at a constant level.
Supplementary Note 8
• In the method of Supplementary Note 6, the step (c) may include supplying the inert gas at a third flow rate, and the step (d may include supplying the inert gas at a fourth flow rate that is less than the third flow rate.
Supplementary Note 9
• In the method of Supplementary Note 8, during the steps (c) and (d), a ratio of the first flow rate to the third flow rate is same as a ratio of the second flow rate to the fourth flow rate.
Supplementary Note 10
• In the method of Supplementary Note 8, during the steps (c) and (d), a ratio of the first flow rate to a sum of the first flow rate and the third flow rate is same as a ratio of the second flow rate to a sum of the second flow rate and the fourth flow rate.
Supplementary Note 11
• In the method of any one ofSupplementary Notes 1 to 10, each of the steps (c) and (d) may include maintaining a partial pressure of the source gas or the reactive gas in respective step at a constant level at least after the inner pressure of the process chamber reaches the predetermined pressure.
Supplementary Note 12
• In the method of any one ofSupplementary Notes 1 to 11, the step (a) may include the steps (c) and (d).
Supplementary Note 13
• In the method of any one ofSupplementary Notes 1 to 12, the step (b) may include the steps (c) and (d).
Supplementary Note 14
• In the method of any one ofSupplementary Notes 1 to 13, the reactive gas may include a carbon-containing gas.
Supplementary Note 15
• In the method of any one ofSupplementary Notes 1 to 14, the reactive gas may include a gas containing carbon and nitrogen.
Supplementary Note 16
• In the method of any one ofSupplementary Notes 1 to 15, the reactive gas may include at least one of a hydrocarbon-based gas and an amine-based gas.
Supplementary Note 17
• According to another embodiment of the present invention, there is provided a substrate processing method, including forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the steps (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
Supplementary Note 18
• According to still another embodiment of the present invention, there is provided a substrate processing apparatus including: a process chamber configured to accommodate a substrate; a source gas supply system configured to supply a source gas into the process chamber; a reactive gas supply system configured to supply a reactive gas into the process chamber; an exhaust system configured to exhaust an inside of the process chamber; a pressure regulator configured to regulate pressure in the process chamber; and a control unit configured to control the source gas supply system, the reactive gas supply system, the exhaust system, and the pressure regulator to form a thin film on the substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the steps (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
Supplementary Note 19
• According to yet another embodiment of the present invention, there is provided a program that causes a computer to perform a sequence of forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the sequences (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.
Supplementary Note 20
• According to yet another embodiment of the present invention, there is provided a non-transitory computer-readable recording medium storing a program that causes a computer to perform a sequence of forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle including: (a) supplying a source gas to the substrate in a process chamber; and (b) supplying a reactive gas to the substrate in the process chamber, wherein at least one of the sequences (a) and (b) includes: (c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and (d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.

Claims (15)

What is claimed is:

1. A method of manufacturing a semiconductor device, comprising:

forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle comprising:

(a) supplying a source gas to the substrate in a process chamber; and

(b) supplying a reactive gas to the substrate in the process chamber,

wherein at least one of (a) and (b) includes:

(c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and

(d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.

2. The method ofclaim 1, wherein (c) comprises setting a degree of opening of an exhaust valve installed at an exhaust line configured to exhaust the inside of the process chamber to a fully closed state, and

(d) comprises opening the exhaust valve.

3. The method ofclaim 1, wherein (c) comprises suspending control of a degree of opening of an exhaust valve installed at an exhaust line configured to exhaust the inside of the process chamber, and

(d) comprises performing the control of the degree of opening of the exhaust valve.

4. The method ofclaim 3, wherein (c) comprises setting the degree of opening of the exhaust valve to a fully closed state.

5. The method ofclaim 1, wherein (c) comprises blocking an exhaust line configured to exhaust the inside of the process chamber, and

(d) comprises opening the exhaust line.

6. The method ofclaim 1, wherein each of (c) and (d) comprises supplying an inert gas together with the source gas or the reactive gas.

7. The method ofclaim 6, wherein each of (c) and (d) comprises maintaining a ratio of a flow rate of the source gas or the reactive gas to that of the inert gas at a constant level.

8. The method ofclaim 6, wherein (c) comprises supplying the inert gas at a third flow rate, and

(d) comprises supplying the inert gas at a fourth flow rate that is less than the third flow rate.

9. The method ofclaim 8, wherein during (c) and (d), a ratio of the first flow rate to the third flow rate is same as a ratio of the second flow rate to the fourth flow rate.

10. The method ofclaim 8, wherein during (c) and (d), a ratio of the first flow rate to a sum of the first flow rate and the third flow rate is same as a ratio of the second flow rate to a sum of the second flow rate and the fourth flow rate.

11. The method ofclaim 1, wherein each of (c) and (d) comprises maintaining a partial pressure of the source gas or the reactive gas in respective step at a constant level at least after the inner pressure of the process chamber reaches the predetermined pressure.

12. The method ofclaim 1, wherein (a) comprises (c) and (d).

13. The method ofclaim 1, wherein (b) comprises (c) and (d).

14. A substrate processing apparatus comprising:

a process chamber configured to accommodate a substrate;

a source gas supply system configured to supply a source gas into the process chamber;

a reactive gas supply system configured to supply a reactive gas into the process chamber;

an exhaust system configured to exhaust an inside of the process chamber;

a pressure regulator configured to regulate pressure in the process chamber; and

a control unit configured to control the source gas supply system, the reactive gas supply system, the exhaust system, and the pressure regulator to form a thin film on the substrate by performing a cycle a predetermined number of times, the cycle comprising;

(a) supplying a source gas to the substrate in a process chamber; and

(b) supplying a reactive gas to the substrate in the process chamber,

wherein at least one of (a) and (b) includes:

(c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and

(d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.

15. A non-transitory computer-readable recording medium storing a program that causes a computer to perform a sequence of forming a thin film on a substrate by performing a cycle a predetermined number of times, the cycle comprising:

(a) supplying a source gas to the substrate in a process chamber; and

(b) supplying a reactive gas to the substrate in the process chamber,

wherein at least one of the sequences (a) and (b) includes:

(c) supplying the source gas or the reactive gas at a first flow rate with an exhaust of an inside of the process chamber being suspended until an inner pressure of the process chamber reaches a predetermined pressure; and

(d) supplying the source gas or the reactive gas at a second flow rate less than the first flow rate with the exhaust of the inside of the process chamber being performed while maintaining the inner pressure of the process chamber at the predetermined pressure after the inner pressure of the process chamber reaches the predetermined pressure.

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